diff --git a/CHANGELOG.md b/CHANGELOG.md
index f300625..2cf20b5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,10 @@ the full mapping table.
 - Clients are constructed through `Ably\PubSub\Server::createHttpClient()`, which declares the server side on the wire. It accepts everything the constructor accepted: an options array, an API key string, a token string, or a `ClientOptions` instance. A client constructed directly declares no side, and is rejected on accounts with monthly-active-user pricing enabled.
 - Removed `AblyRest::setAblyAgentHeader()` and `AblyRest::setLibraryFlavourString()`, replaced by the per-client `agents` client option.
 - Removed `ably-loader.php`; Composer's autoloader is the only supported install path.
+- Added the `endpoint` client option (REC1, REC2), which is now the only way to choose where the client connects. The default primary domain is `main.realtime.ably.net`, with fallback hosts `main.[a-e].fallback.ably-realtime.com`.
+- Removed the `environment` and `restHost` client options in favour of `endpoint`. They are now ignored if passed, so a client still setting `environment` connects to production.
+- Setting `port` or `tlsPort` no longer disables the default fallback hosts; a hostname `endpoint` does.
+- `ClientOptions::getPrimaryRestHost()` is now `getPrimaryDomain()`. `Defaults::$restHost`, `Defaults::$realtimeHost` and `Defaults::getEnvironmentFallbackHosts()` are replaced by `Defaults::$endpoint`, `Defaults::getPrimaryDomain()` and `Defaults::getEndpointFallbackHosts()`.
 - Removed the `demo/` Heroku application and its `Procfile`.
 - The minimum supported PHP version is now 8.1; the SDK is tested on 8.1 through 8.5.
 
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index def08b9..e22e01f 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -3,6 +3,6 @@
 1. Fork it
 2. Create your feature branch (`git checkout -b my-new-feature`)
 3. Commit your changes (`git commit -am 'Add some feature'`)
-4. Ensure you have added suitable tests and the test suite is passing (run `vendor/bin/phpunit`)
+4. Ensure you have added suitable tests and the test suite is passing (run `vendor/bin/phpunit`). Tests run against the `nonprod:sandbox` endpoint; set `ABLY_ENDPOINT` to use another.
 4. Push to the branch (`git push origin my-new-feature`)
 5. Create a new Pull Request
\ No newline at end of file
diff --git a/UPDATING.md b/UPDATING.md
index f669df4..7778488 100644
--- a/UPDATING.md
+++ b/UPDATING.md
@@ -6,7 +6,7 @@ Version 2.0.0 ships from a new package, `ably/pubsub-server`, under a new namesp
 
 Under monthly-active-user pricing the platform has to classify every connection as device-side or server-side. The new package declares that automatically, on every request, in the `Ably-Agent` header; the old constructor cannot declare anything. That is the forcing function for this migration: once monthly-active-user pricing is live, `new Ably\AblyRest(...)` from `ably/ably-php` is rejected on accounts where it is enabled.
 
-The client `Server::createHttpClient()` returns is the same REST client as before, renamed from `AblyRest` to `PubSubHttpClient`. Channels, message publishing, history, presence, authentication, push admin, crypto and every `ClientOptions` key behave exactly as they did in 1.x. For most applications the migration is confined to the `composer require` line, the `use` statements, and the constructor call.
+The client `Server::createHttpClient()` returns is the same REST client as before, renamed from `AblyRest` to `PubSubHttpClient`. Channels, message publishing, history, presence, authentication, push admin and crypto behave exactly as they did in 1.x. The one change to `ClientOptions` is how the client chooses where to connect: the `endpoint` option replaces `environment` and `restHost` (see [Endpoint](#endpoint-replaces-environment-and-resthost)). For most applications the migration is confined to the `composer require` line, the `use` statements, the constructor call, and any host options.
 
 ### Mapping
 
@@ -20,6 +20,7 @@ The client `Server::createHttpClient()` returns is the same REST client as befor
 | `require 'ably-loader.php';` | removed — use Composer's autoloader (`vendor/autoload.php`) |
 | PHP 7.2 – 8.0 | PHP `^8.1` (tested on 8.1 – 8.5) |
 | `\Ably\AblyRest` type hints | `\Ably\PubSub\PubSubHttpClient` ([091d](https://ably.atlassian.net/wiki/spaces/product/pages/5363957781)) |
+| `'environment' => 'sandbox'` / `'restHost' => '…'` | `'endpoint' => …` (see [Endpoint](#endpoint-replaces-environment-and-resthost)) |
 
 Every class moves namespace, and `AblyRest` is the only one that also changes name, so the rename is mechanical: replace the prefix `Ably\` with `Ably\PubSub\` throughout — including in type hints, `catch` blocks and fully-qualified string class names — and then `AblyRest` with `PubSubHttpClient`.
 
@@ -41,6 +42,42 @@ $ably->channel('test-channel')->publish('test-event', 'hello world');
 
 `createHttpClient()` accepts everything the 1.x constructor accepted: an options array, an API key string, a token string, or a `ClientOptions` instance. A `ClientOptions` instance you pass in is copied rather than mutated.
 
+### Endpoint replaces environment and restHost
+
+The `endpoint` client option is now the only way to choose where the client connects. `environment` and `restHost` are removed. Like any other unknown key, they are now ignored, so a client still passing `'environment' => 'sandbox'` connects to production: replace them before upgrading.
+
+| 1.x | 2.0 |
+| --- | --- |
+| no host options | no change; traffic moves from `rest.ably.io` to `main.realtime.ably.net` |
+| `'environment' => 'sandbox'` | `'endpoint' => 'nonprod:sandbox'` |
+| `'environment' => 'acme'` (dedicated cluster) | `'endpoint' => 'acme'` |
+| `'restHost' => 'localhost'` | `'endpoint' => 'localhost'` |
+| `'restHost' => 'rest.example.com'` | `'endpoint' => 'rest.example.com'` |
+| custom `'fallbackHosts' => […]` | unchanged |
+
+How `endpoint` resolves:
+
+| `endpoint` | Primary domain | Default fallback hosts |
+| --- | --- | --- |
+| unset (`main`) | `main.realtime.ably.net` | `main.[a-e].fallback.ably-realtime.com` |
+| `[id]`, e.g. `acme` | `[id].realtime.ably.net` | `[id].[a-e].fallback.ably-realtime.com` |
+| `nonprod:[id]`, e.g. `nonprod:sandbox` | `[id].realtime.ably-nonprod.net` | `[id].[a-e].fallback.ably-realtime-nonprod.com` |
+| a hostname: contains `.` or `::`, or is `localhost` | the value as given | none |
+
+A non-empty `fallbackHosts` still replaces the default fallback hosts. Setting `port` or `tlsPort` no longer disables the default fallback hosts; only a hostname `endpoint` does.
+
+```php
+// 1.x
+$ably = new AblyRest(['key' => getenv('ABLY_API_KEY'), 'environment' => 'sandbox']);
+
+// 2.0
+$ably = Server::createHttpClient(['key' => getenv('ABLY_API_KEY'), 'endpoint' => 'nonprod:sandbox']);
+```
+
+`ClientOptions::getPrimaryRestHost()` is renamed `getPrimaryDomain()`, and `Defaults::$restHost`, `Defaults::$realtimeHost` and `Defaults::getEnvironmentFallbackHosts()` are replaced by `Defaults::$endpoint`, `Defaults::getPrimaryDomain()` and `Defaults::getEndpointFallbackHosts()`.
+
+Firewall allowlists and outbound proxies must allow `*.realtime.ably.net` and `*.fallback.ably-realtime.com` in place of `rest.ably.io` and `*.ably-realtime.com`.
+
 ### Declaring the side
 
 Construct through the door. `new Ably\PubSub\PubSubHttpClient(...)` still works — the library and its own tests use it — but it declares no side, and will be rejected on monthly-active-user-enabled accounts just as the 1.x constructor is. The door produces:
@@ -67,6 +104,7 @@ The `agents` option is per-client, unlike the process-global static setters it r
 * `AblyRest::setAblyAgentHeader()` and `AblyRest::$agents` — replaced by the per-client `agents` option.
 * `AblyRest::setLibraryFlavourString()` — already deprecated in 1.x; replaced by the same option.
 * `ably-loader.php`, the hand-rolled autoloader — Composer is the only supported install path.
+* The `environment` and `restHost` client options — replaced by `endpoint`. They are ignored if passed.
 * The `demo/` Heroku application and its `Procfile`.
 * PHP 7.2 – 8.0 support.
 
@@ -75,7 +113,7 @@ The `agents` option is per-client, unlike the process-global static setters it r
 ### Unchanged
 
 * The REST client and its whole surface: `channel()`, `channels`, publishing, message history, presence and presence history, `auth`, token requests and token issuing, `push` admin, `stats`, `time()`, and crypto.
-* Every `ClientOptions` key, and the array / key-string / token-string / `ClientOptions` forms of the constructor argument.
+* Every `ClientOptions` key other than the host options above, and the array / key-string / token-string / `ClientOptions` forms of the constructor argument.
 * Message and error semantics, including `AblyException` and its codes.
 * Requirements: `ext-json`, `ext-curl`, `ext-openssl`, and `rybakit/msgpack` for the msgpack protocol.
 
diff --git a/src/Defaults.php b/src/Defaults.php
index 151178f..00b6ce0 100644
--- a/src/Defaults.php
+++ b/src/Defaults.php
@@ -5,8 +5,7 @@ class Defaults {
     const API_VERSION = '2';
     const LIB_VERSION = '2.0.0';
 
-    static $restHost = "rest.ably.io";
-    static $realtimeHost = "realtime.ably.io";
+    static $endpoint = 'main';
     static $port = 80;
     static $tlsPort = 443;
 
@@ -14,20 +13,55 @@ class Defaults {
     static $internetCheckOk = "yes\n";
 
     static $fallbackHosts = [
-        'a.ably-realtime.com',
-        'b.ably-realtime.com',
-        'c.ably-realtime.com',
-        'd.ably-realtime.com',
-        'e.ably-realtime.com',
+        'main.a.fallback.ably-realtime.com',
+        'main.b.fallback.ably-realtime.com',
+        'main.c.fallback.ably-realtime.com',
+        'main.d.fallback.ably-realtime.com',
+        'main.e.fallback.ably-realtime.com',
     ];
 
-    static function getEnvironmentFallbackHosts($environment) {
-        return [
-            $environment."-a-fallback.ably-realtime.com",
-            $environment."-b-fallback.ably-realtime.com",
-            $environment."-c-fallback.ably-realtime.com",
-            $environment."-d-fallback.ably-realtime.com",
-            $environment."-e-fallback.ably-realtime.com"
-        ];
+    const NONPROD_PREFIX = 'nonprod:';
+
+    /**
+     * An endpoint is taken as a hostname rather than a routing policy id when
+     * it contains a `.` or `::`, or is `localhost` (REC1b2).
+     */
+    static function isHostname($endpoint) {
+        return strpos($endpoint, '.') !== false
+            || strpos($endpoint, '::') !== false
+            || $endpoint === 'localhost';
+    }
+
+    /**
+     * Resolves the primary domain from an `endpoint` client option (REC1).
+     */
+    static function getPrimaryDomain($endpoint) {
+        if (self::isHostname($endpoint)) {
+            return $endpoint; // REC1b2
+        }
+        if (strpos($endpoint, self::NONPROD_PREFIX) === 0) {
+            return substr($endpoint, strlen(self::NONPROD_PREFIX)).'.realtime.ably-nonprod.net'; // REC1b3
+        }
+        return $endpoint.'.realtime.ably.net'; // REC1b4
+    }
+
+    /**
+     * Resolves the default fallback domains for an `endpoint` client option (REC2c).
+     */
+    static function getEndpointFallbackHosts($endpoint) {
+        if (self::isHostname($endpoint)) {
+            return []; // REC2c2
+        }
+        if (strpos($endpoint, self::NONPROD_PREFIX) === 0) {
+            $id = substr($endpoint, strlen(self::NONPROD_PREFIX));
+            return self::fallbackHostsFor($id, 'ably-realtime-nonprod.com'); // REC2c3
+        }
+        return self::fallbackHostsFor($endpoint, 'ably-realtime.com'); // REC2c1, REC2c4
+    }
+
+    private static function fallbackHostsFor($id, $domain) {
+        return array_map(function ($letter) use ($id, $domain) {
+            return $id.'.'.$letter.'.fallback.'.$domain;
+        }, ['a', 'b', 'c', 'd', 'e']);
     }
 }
diff --git a/src/Host.php b/src/Host.php
index d62c2c5..302e2e8 100644
--- a/src/Host.php
+++ b/src/Host.php
@@ -8,7 +8,7 @@ class Host {
 
     public function __construct($clientOptions)
     {
-        $this->primaryHost = $clientOptions->getPrimaryRestHost();
+        $this->primaryHost = $clientOptions->getPrimaryDomain();
         $this->fallbackHosts = $clientOptions->getFallbackHosts();
         $this->hostCache = new HostCache($clientOptions->fallbackRetryTimeout);
     }
diff --git a/src/Models/ClientOptions.php b/src/Models/ClientOptions.php
index 6204061..a285d3a 100644
--- a/src/Models/ClientOptions.php
+++ b/src/Models/ClientOptions.php
@@ -35,10 +35,14 @@ class ClientOptions extends AuthOptions {
     public $useBinaryProtocol = true;
 
     /**
-     * @var string alternate server domain
-     * For development environments only.
+     * @var string|null where the client connects (REC1), default `main`.
+     * One of: a routing policy id such as `main` or a dedicated cluster id,
+     * which resolves to `[id].realtime.ably.net`; `nonprod:[id]`, which
+     * resolves to `[id].realtime.ably-nonprod.net`; or a hostname (anything
+     * containing `.` or `::`, or `localhost`), which is used as given and has
+     * no default fallback hosts.
      */
-    public $restHost;
+    public $endpoint;
 
     /**
      * @var integer Allows a non-default Ably non-TLS port to be used.
@@ -53,19 +57,13 @@ class ClientOptions extends AuthOptions {
     public $tlsPort;
 
     /**
-     * @var string optional prefix to be prepended to $restHost
-     * Example: 'sandbox' -> 'sandbox-rest.ably.io'
-     */
-    public $environment;
-
-    /**
-     * @var string[] fallback hosts, used when connection to default host fails, populated automatically
+     * @var string[] fallback hosts, used when connection to the primary domain fails; when empty, derived from $endpoint
      */
     public $fallbackHosts = [];
 
     /**
      * @var integer – default 600000 (10 minutes) the period in milliseconds
-     * before HTTP requests are retried against the default endpoint
+     * before HTTP requests are retried against the primary domain
      */
     public $fallbackRetryTimeout = 600000;
 
@@ -151,35 +149,27 @@ public static function normalizeConstructorArgument( $options ) {
         return $options;
     }
 
-    private function isProductionEnvironment() {
-        return empty($this->environment) || strcasecmp($this->environment, "production") == 0;
-    }
-
-    private function isDefaultPort() {
-        return $this->tls ? $this->tlsPort == Defaults::$tlsPort : $this->port == Defaults::$port;
-    }
-
     private function activePort() {
         return $this->tls ? $this->tlsPort : $this->port;
     }
 
-    private function isDefaultRestHost() {
-        return $this->restHost == Defaults::$restHost;
-    }
-
-    public function getPrimaryRestHost() {
-        if ($this->isDefaultRestHost()) {
-            return $this->isProductionEnvironment() ? $this->restHost : $this->environment.'-'.$this->restHost;
-        }
-        return $this->restHost;
+    /**
+     * The domain both REST requests and, in SDKs that have one, the realtime
+     * connection use (REC1, RSC25).
+     */
+    public function getPrimaryDomain() {
+        return Defaults::getPrimaryDomain($this->endpoint);
     }
 
+    /**
+     * An explicit, non-empty `fallbackHosts` replaces the defaults (REC2a2);
+     * otherwise the defaults are derived from `endpoint` (REC2c).
+     */
     public function getFallbackHosts() {
-        $fallbacks = $this->fallbackHosts ?? [];
-        if (empty($this->fallbackHosts) && $this->isDefaultRestHost() && $this->isDefaultPort()) {
-            $fallbacks = $this->isProductionEnvironment() ? Defaults::$fallbackHosts : Defaults::getEnvironmentFallbackHosts($this->environment);
+        if (!empty($this->fallbackHosts)) {
+            return $this->fallbackHosts;
         }
-        return $fallbacks;
+        return Defaults::getEndpointFallbackHosts($this->endpoint);
     }
 
     public function getHostUrl($host) {
@@ -188,8 +178,8 @@ public function getHostUrl($host) {
 
     public function __construct( $options = [] ) {
         parent::__construct( $options );
-        if (empty($this->restHost)) {
-            $this->restHost = Defaults::$restHost;
+        if (empty($this->endpoint)) {
+            $this->endpoint = Defaults::$endpoint;
         }
         if (empty($this->port)) {
             $this->port = Defaults::$port;
diff --git a/src/PubSubHttpClient.php b/src/PubSubHttpClient.php
index 78560bd..b03330c 100644
--- a/src/PubSubHttpClient.php
+++ b/src/PubSubHttpClient.php
@@ -219,7 +219,7 @@ public function requestInternal( $method, $path, $headers = [], $params = [], $r
             $hostUrl = $this->options->getHostUrl($host). $path;
             try {
                 $updatedHeaders = $mergedHeaders;
-                if ($host != $this->options->getPrimaryRestHost()) { // set hostHeader for fallback host (RSC15j)
+                if ($host != $this->options->getPrimaryDomain()) { // set hostHeader for fallback host (RSC15j)
                     $updatedHeaders[] = "Host: " . $host;
                 }
                 $response = $this->http->request( $method, $hostUrl, $updatedHeaders, $params );
diff --git a/tests/ChannelIdempotentTest.php b/tests/ChannelIdempotentTest.php
index a8e23ee..142e8fc 100644
--- a/tests/ChannelIdempotentTest.php
+++ b/tests/ChannelIdempotentTest.php
@@ -168,9 +168,9 @@ public function testIdempotentLibraryGeneratedPublish() {
             'idempotentRestPublishing' => true,
             'httpClass' => 'tests\HttpMockIdempotent',
             'fallbackHosts' => [
-                self::$ably->options->getPrimaryRestHost(),
-                self::$ably->options->getPrimaryRestHost(),
-                self::$ably->options->getPrimaryRestHost(),
+                self::$ably->options->getPrimaryDomain(),
+                self::$ably->options->getPrimaryDomain(),
+                self::$ably->options->getPrimaryDomain(),
             ],
         ] ) );
 
diff --git a/tests/ChannelMessagesTest.php b/tests/ChannelMessagesTest.php
index 638ec98..dc3de2c 100644
--- a/tests/ChannelMessagesTest.php
+++ b/tests/ChannelMessagesTest.php
@@ -468,7 +468,7 @@ public function testEncodingInteroperabilityRawToAbly() {
 
         $defaultOpts = new \Ably\PubSub\Models\ClientOptions( self::$defaultOptions );
         $http = new \Ably\PubSub\Http( $defaultOpts ); // initialize http class for raw requests with default timeouts
-        $server = 'https://' . $defaultOpts->getPrimaryRestHost();
+        $server = 'https://' . $defaultOpts->getPrimaryDomain();
 
         $messages = [];
         foreach ($fixture->messages as $i => $testMsgData) {
@@ -514,7 +514,7 @@ public function testEncodingInteroperabilityAblyToRaw() {
 
         $defaultOpts = new \Ably\PubSub\Models\ClientOptions( self::$defaultOptions );
         $http = new \Ably\PubSub\Http( $defaultOpts ); // initialize http class for raw requests with default timeouts
-        $server = 'https://' . $defaultOpts->getPrimaryRestHost();
+        $server = 'https://' . $defaultOpts->getPrimaryDomain();
 
         $messages = [];
         foreach ($fixture->messages as $i => $testMsgData) {
diff --git a/tests/ClientOptionsTest.php b/tests/ClientOptionsTest.php
index dbaa813..690cbb1 100644
--- a/tests/ClientOptionsTest.php
+++ b/tests/ClientOptionsTest.php
@@ -2,18 +2,18 @@
 namespace tests;
 use Ably\PubSub\Defaults;
 use Ably\PubSub\Models\ClientOptions;
-use http\Env;
 
 /**
  * @testdox RSC15b
  */
 class ClientOptionsTest extends \PHPUnit\Framework\TestCase {
     /**
-     * @testdox RSC15e RSC15g3
+     * @testdox RSC15e REC1a REC2c1
      */
     public function testWithDefaultOptions() {
         $clientOptions = new ClientOptions();
-        self::assertEquals('rest.ably.io', $clientOptions->getPrimaryRestHost());
+        self::assertEquals('main', $clientOptions->endpoint);
+        self::assertEquals('main.realtime.ably.net', $clientOptions->getPrimaryDomain());
         self::assertTrue($clientOptions->tls);
         self::assertEquals(443, $clientOptions->tlsPort);
         $fallbackHosts = $clientOptions->getFallbackHosts();
@@ -22,74 +22,77 @@ public function testWithDefaultOptions() {
     }
 
     /**
-     * @testdox RSC15h
+     * @testdox REC1b4 REC2c4
      */
-    public function testWithProductionEnvironment() {
-        $clientOptions = new ClientOptions();
-        $clientOptions->environment = "Production";
-        self::assertEquals('rest.ably.io', $clientOptions->getPrimaryRestHost());
-        self::assertTrue($clientOptions->tls);
-        self::assertEquals(443, $clientOptions->tlsPort);
-        $fallbackHosts = $clientOptions->getFallbackHosts();
-        sort($fallbackHosts);
-        $this->assertEquals(Defaults::$fallbackHosts, $fallbackHosts);
+    public function testWithRoutingPolicyEndpoint() {
+        $clientOptions = new ClientOptions(['endpoint' => 'acme']);
+        self::assertEquals('acme.realtime.ably.net', $clientOptions->getPrimaryDomain());
+        self::assertEquals([
+            'acme.a.fallback.ably-realtime.com',
+            'acme.b.fallback.ably-realtime.com',
+            'acme.c.fallback.ably-realtime.com',
+            'acme.d.fallback.ably-realtime.com',
+            'acme.e.fallback.ably-realtime.com',
+        ], $clientOptions->getFallbackHosts());
     }
 
     /**
-     * @testdox RSC15g2 RTC1e
+     * @testdox REC1b3 REC2c3
      */
-    public function testWithCustomEnvironment() {
-        $clientOptions = new ClientOptions();
-        $clientOptions->environment = "sandbox";
-        self::assertEquals('sandbox-rest.ably.io', $clientOptions->getPrimaryRestHost());
-        self::assertTrue($clientOptions->tls);
-        self::assertEquals(443, $clientOptions->tlsPort);
-        $fallbackHosts = $clientOptions->getFallbackHosts();
-        sort($fallbackHosts);
-        $this->assertEquals(Defaults::getEnvironmentFallbackHosts('sandbox'), $fallbackHosts);
+    public function testWithNonprodEndpoint() {
+        $clientOptions = new ClientOptions(['endpoint' => 'nonprod:sandbox']);
+        self::assertEquals('sandbox.realtime.ably-nonprod.net', $clientOptions->getPrimaryDomain());
+        self::assertEquals([
+            'sandbox.a.fallback.ably-realtime-nonprod.com',
+            'sandbox.b.fallback.ably-realtime-nonprod.com',
+            'sandbox.c.fallback.ably-realtime-nonprod.com',
+            'sandbox.d.fallback.ably-realtime-nonprod.com',
+            'sandbox.e.fallback.ably-realtime-nonprod.com',
+        ], $clientOptions->getFallbackHosts());
+    }
+
+    public static function hostnameEndpointProvider() {
+        return [
+            ['foo.example.com'],
+            ['localhost'],
+            ['127.0.0.1'],
+            ['::1'],
+        ];
     }
 
     /**
-     * @testdox RSC11b RTN17b RTC1e
+     * @testdox REC1b2 REC2c2
+     * @dataProvider hostnameEndpointProvider
      */
-    public function testWithCustomEnvironmentAndNonDefaultPorts() {
-        $clientOptions = new ClientOptions();
-        $clientOptions->environment = "local";
-        $clientOptions->port = 8080;
-        $clientOptions->tlsPort = 8081;
-        self::assertEquals('local-rest.ably.io', $clientOptions->getPrimaryRestHost());
-        self::assertEquals(8080, $clientOptions->port);
-        self::assertEquals(8081, $clientOptions->tlsPort);
-        self::assertTrue($clientOptions->tls);
-        $fallbackHosts = $clientOptions->getFallbackHosts();
-        self::assertEmpty($fallbackHosts);
+    public function testWithHostnameEndpoint($endpoint) {
+        $clientOptions = new ClientOptions(['endpoint' => $endpoint]);
+        self::assertEquals($endpoint, $clientOptions->getPrimaryDomain());
+        self::assertEmpty($clientOptions->getFallbackHosts());
     }
 
     /**
-     * @testdox RSC11
+     * Non-default ports do not suppress the default fallback hosts; only a
+     * hostname endpoint does (REC2c).
+     * @testdox REC2c1
      */
-    public function testWithCustomRestHost() {
-        $clientOptions = new ClientOptions();
-        $clientOptions->restHost = "test.org";
-        self::assertEquals('test.org', $clientOptions->getPrimaryRestHost());
-        self::assertEquals(80, $clientOptions->port);
-        self::assertEquals(443, $clientOptions->tlsPort);
-        self::assertTrue($clientOptions->tls);
-        $fallbackHosts = $clientOptions->getFallbackHosts();
-        self::assertEmpty($fallbackHosts);
+    public function testWithNonDefaultPorts() {
+        $clientOptions = new ClientOptions(['port' => 8080, 'tlsPort' => 8081]);
+        self::assertEquals(8080, $clientOptions->port);
+        self::assertEquals(8081, $clientOptions->tlsPort);
+        self::assertEquals('main.realtime.ably.net', $clientOptions->getPrimaryDomain());
+        self::assertEquals(Defaults::$fallbackHosts, $clientOptions->getFallbackHosts());
     }
 
     /**
-     * @testdox RSC15g1
+     * @testdox RSC15g1 REC2a2
      */
     public function testWithFallbacks() {
-        $clientOptions = new ClientOptions();
-        $clientOptions->fallbackHosts = ["a.example.com", "b.example.com"];
-        self::assertEquals('rest.ably.io', $clientOptions->getPrimaryRestHost());
-        self::assertTrue($clientOptions->tls);
-        self::assertEquals(443, $clientOptions->tlsPort);
-        $fallbackHosts = $clientOptions->getFallbackHosts();
-        sort($fallbackHosts);
-        self::assertEquals(["a.example.com", "b.example.com"], $fallbackHosts);
+        foreach (['main', 'nonprod:sandbox', 'foo.example.com'] as $endpoint) {
+            $clientOptions = new ClientOptions([
+                'endpoint' => $endpoint,
+                'fallbackHosts' => ["a.example.com", "b.example.com"],
+            ]);
+            self::assertEquals(["a.example.com", "b.example.com"], $clientOptions->getFallbackHosts());
+        }
     }
 }
diff --git a/tests/DefaultsTest.php b/tests/DefaultsTest.php
index 82e4d91..1f975e0 100644
--- a/tests/DefaultsTest.php
+++ b/tests/DefaultsTest.php
@@ -1,37 +1,29 @@
 <?php
 namespace tests;
 use Ably\PubSub\Defaults;
-use Ably\PubSub\Models\ClientOptions;
 
 class DefaultsTest extends \PHPUnit\Framework\TestCase {
 
     /**
-     * @testdox RSC15h
+     * @testdox REC2c1
      */
     public function testFallbackHosts() {
         $expectedFallbackHosts = [
-            "a.ably-realtime.com",
-            "b.ably-realtime.com",
-            "c.ably-realtime.com",
-            "d.ably-realtime.com",
-            "e.ably-realtime.com"
+            "main.a.fallback.ably-realtime.com",
+            "main.b.fallback.ably-realtime.com",
+            "main.c.fallback.ably-realtime.com",
+            "main.d.fallback.ably-realtime.com",
+            "main.e.fallback.ably-realtime.com"
         ];
-        $fallbackHosts = Defaults::$fallbackHosts;
-        $this->assertEquals($expectedFallbackHosts, $fallbackHosts);
+        $this->assertEquals($expectedFallbackHosts, Defaults::$fallbackHosts);
+        $this->assertEquals($expectedFallbackHosts, Defaults::getEndpointFallbackHosts(Defaults::$endpoint));
     }
 
     /**
-     * @testdox RSC15i
+     * @testdox REC1a
      */
-    public function testEnvironmentFallbackHosts() {
-        $expectedFallbackHosts = [
-            "sandbox-a-fallback.ably-realtime.com",
-            "sandbox-b-fallback.ably-realtime.com",
-            "sandbox-c-fallback.ably-realtime.com",
-            "sandbox-d-fallback.ably-realtime.com",
-            "sandbox-e-fallback.ably-realtime.com"
-        ];
-        $fallbackHosts = Defaults::getEnvironmentFallbackHosts("sandbox");
-        $this->assertEquals($expectedFallbackHosts, $fallbackHosts);
+    public function testDefaultEndpoint() {
+        $this->assertEquals('main', Defaults::$endpoint);
+        $this->assertEquals('main.realtime.ably.net', Defaults::getPrimaryDomain(Defaults::$endpoint));
     }
 }
diff --git a/tests/HostCacheTest.php b/tests/HostCacheTest.php
index 315347e..55eb042 100644
--- a/tests/HostCacheTest.php
+++ b/tests/HostCacheTest.php
@@ -1,7 +1,6 @@
 <?php
 namespace tests;
 
-use Ably\PubSub\Defaults;
 use Ably\PubSub\HostCache;
 
 /**
@@ -14,8 +13,8 @@ class HostCacheTest extends \PHPUnit\Framework\TestCase {
      */
     public function testHost() {
         $hostCache = new HostCache(3000);
-        $hostCache->put(Defaults::$restHost);
-        self::assertEquals("rest.ably.io", $hostCache->get());
+        $hostCache->put("main.realtime.ably.net");
+        self::assertEquals("main.realtime.ably.net", $hostCache->get());
     }
 
     /**
@@ -23,7 +22,7 @@ public function testHost() {
      */
     public function testExpiredHost() {
         $hostCache = new HostCache(999);
-        $hostCache->put(Defaults::$restHost);
+        $hostCache->put("main.realtime.ably.net");
         sleep(1);
         self::assertEquals("", $hostCache->get());
     }
diff --git a/tests/HostTest.php b/tests/HostTest.php
index 928d880..0a10b2c 100644
--- a/tests/HostTest.php
+++ b/tests/HostTest.php
@@ -17,15 +17,15 @@ public function testFallbacksInRandomOrder() {
         $restHosts = new Host($clientOptions);
         // All expected hosts supposed to be tried upon
         $expectedFallbackHosts = [
-			"a.ably-realtime.com",
-			"b.ably-realtime.com",
-			"c.ably-realtime.com",
-			"d.ably-realtime.com",
-			"e.ably-realtime.com",
+			"main.a.fallback.ably-realtime.com",
+			"main.b.fallback.ably-realtime.com",
+			"main.c.fallback.ably-realtime.com",
+			"main.d.fallback.ably-realtime.com",
+			"main.e.fallback.ably-realtime.com",
 		];
 
         $prefHost = $restHosts->getPreferredHost();
-        self::assertEquals("rest.ably.io", $prefHost);
+        self::assertEquals("main.realtime.ably.net", $prefHost);
 
         $fallbacks = iterator_to_array($restHosts->fallbackHosts($prefHost));
         self::assertNotEquals($expectedFallbackHosts, $fallbacks);
@@ -42,20 +42,20 @@ public function testFallbacksOtherThanPreferredHost() {
         $restHosts = new Host($clientOptions);
         // All expected hosts supposed to be tried upon
         $expectedFallbackHosts = [
-            "rest.ably.io",
-            "a.ably-realtime.com",
-            "c.ably-realtime.com",
-            "d.ably-realtime.com",
-            "e.ably-realtime.com",
+            "main.realtime.ably.net",
+            "main.a.fallback.ably-realtime.com",
+            "main.c.fallback.ably-realtime.com",
+            "main.d.fallback.ably-realtime.com",
+            "main.e.fallback.ably-realtime.com",
         ];
 
-        $restHosts->setPreferredHost("b.ably-realtime.com");
+        $restHosts->setPreferredHost("main.b.fallback.ably-realtime.com");
 
         $prefHost = $restHosts->getPreferredHost();
-        self::assertEquals("b.ably-realtime.com", $prefHost);
+        self::assertEquals("main.b.fallback.ably-realtime.com", $prefHost);
 
         $fallbacks = iterator_to_array($restHosts->fallbackHosts($prefHost));
-        self::assertEquals("rest.ably.io", $fallbacks[0]);
+        self::assertEquals("main.realtime.ably.net", $fallbacks[0]);
 
         sort($fallbacks);
         sort($expectedFallbackHosts);
@@ -70,16 +70,16 @@ public function testGetAllFallbacksWithNoPreferredHost() {
         $restHosts = new Host($clientOptions);
         // All expected hosts supposed to be tried upon
         $expectedFallbackHosts = [
-            "rest.ably.io",
-            "b.ably-realtime.com",
-            "a.ably-realtime.com",
-            "c.ably-realtime.com",
-            "d.ably-realtime.com",
-            "e.ably-realtime.com",
+            "main.realtime.ably.net",
+            "main.b.fallback.ably-realtime.com",
+            "main.a.fallback.ably-realtime.com",
+            "main.c.fallback.ably-realtime.com",
+            "main.d.fallback.ably-realtime.com",
+            "main.e.fallback.ably-realtime.com",
         ];
 
         $fallbacks = iterator_to_array($restHosts->fallbackHosts(""));
-        self::assertEquals("rest.ably.io", $fallbacks[0]);
+        self::assertEquals("main.realtime.ably.net", $fallbacks[0]);
 
         sort($fallbacks);
         sort($expectedFallbackHosts);
@@ -93,7 +93,7 @@ public function testGetPrimaryHostIfNothingIsCached() {
         $clientOptions = new ClientOptions();
         $restHosts = new Host($clientOptions);
         $prefHost = $restHosts->getPreferredHost();
-        self::assertEquals("rest.ably.io", $prefHost);
+        self::assertEquals("main.realtime.ably.net", $prefHost);
     }
 }
 
diff --git a/tests/PubSubHttpClientTest.php b/tests/PubSubHttpClientTest.php
index 0436bca..60c344d 100644
--- a/tests/PubSubHttpClientTest.php
+++ b/tests/PubSubHttpClientTest.php
@@ -76,12 +76,13 @@ public function testInitLibWithTokenDetailsOption() {
     }
 
     /**
-     * Init library with a specified host
+     * Init library with a hostname endpoint
+     * @testdox REC1b2
      */
     public function testInitLibWithSpecifiedHost() {
         $opts = [
             'key' => 'fake.key:veryFake',
-            'restHost'  => 'some.other.host',
+            'endpoint'  => 'some.other.host',
             'httpClass' => 'tests\HttpMockInitTest',
         ];
         $ably = new PubSubHttpClient( $opts );
@@ -95,21 +96,21 @@ public function testInitLibWithSpecifiedHost() {
     public function testInitLibWithSpecifiedPort() {
         $opts = [
             'key' => 'fake.key:veryFake',
-            'restHost'  => 'some.other.host',
+            'endpoint'  => 'some.other.host',
             'tlsPort' => 999,
             'httpClass' => 'tests\HttpMockInitTest',
         ];
         $ably = new PubSubHttpClient( $opts );
         $ably->time(); // make a request
         $this->assertStringContainsString(
-            'https://' . $opts['restHost'] . ':' . $opts['tlsPort'],
+            'https://' . $opts['endpoint'] . ':' . $opts['tlsPort'],
             $ably->http->lastUrl,
             'Unexpected host/port mismatch'
         );
 
         $opts = [
             'token' => 'fakeToken',
-            'restHost'  => 'some.other.host',
+            'endpoint'  => 'some.other.host',
             'port' => 999,
             'tls' => false,
             'httpClass' => 'tests\HttpMockInitTest',
@@ -117,27 +118,28 @@ public function testInitLibWithSpecifiedPort() {
         $ably = new PubSubHttpClient( $opts );
         $ably->time(); // make a request
         $this->assertStringContainsString(
-            'http://' . $opts['restHost'] . ':' . $opts['port'],
+            'http://' . $opts['endpoint'] . ':' . $opts['port'],
             $ably->http->lastUrl,
             'Unexpected host/port mismatch'
         );
     }
 
     /**
-     * Init library with specified environment
+     * Init library with a nonprod routing policy endpoint
+     * @testdox REC1b3
      */
-    public function testInitLibWithSpecifiedEnv() {
+    public function testInitLibWithNonprodEndpoint() {
         $ably = new PubSubHttpClient( [
             'key' => 'fake.key:veryFake',
-            'environment'  => 'sandbox',
+            'endpoint'  => 'nonprod:sandbox',
             'httpClass' => 'tests\HttpMockInitTest',
         ] );
         $ably->time(); // make a request
-        $this->assertEquals( 'https://sandbox-rest.ably.io:443/time', $ably->http->lastUrl, 'Unexpected host mismatch' );
+        $this->assertEquals( 'https://sandbox.realtime.ably-nonprod.net:443/time', $ably->http->lastUrl, 'Unexpected host mismatch' );
     }
 
     /**
-     * Verify encrypted defaults to true, makes a request to https://rest.ably.io/...
+     * Verify encrypted defaults to true, makes a request to https://main.realtime.ably.net/...
      */
     public function testTLSDefaultIsTrue() {
         $opts = [
@@ -146,11 +148,11 @@ public function testTLSDefaultIsTrue() {
         ];
         $ably = new PubSubHttpClient( $opts );
         $ably->time(); // make a request
-        $this->assertMatchesRegularExpression( '/^https:\/\/rest\.ably\.io/', $ably->http->lastUrl, 'Unexpected scheme/url mismatch' );
+        $this->assertMatchesRegularExpression( '/^https:\/\/main\.realtime\.ably\.net/', $ably->http->lastUrl, 'Unexpected scheme/url mismatch' );
     }
 
     /**
-     * Verify encrypted can be set to false, makes a request to http://rest.ably.io/...
+     * Verify encrypted can be set to false, makes a request to http://main.realtime.ably.net/...
      */
     public function testTLSCanBeFalse() {
         $opts = [
@@ -160,11 +162,11 @@ public function testTLSCanBeFalse() {
         ];
         $ably = new PubSubHttpClient( $opts );
         $ably->time(); // make a request
-        $this->assertMatchesRegularExpression( '/^http:\/\/rest\.ably\.io/', $ably->http->lastUrl, 'Unexpected scheme/url mismatch' );
+        $this->assertMatchesRegularExpression( '/^http:\/\/main\.realtime\.ably\.net/', $ably->http->lastUrl, 'Unexpected scheme/url mismatch' );
     }
 
     /**
-     * Verify that connection is encrypted when set to true explicitly, makes a request to https://rest.ably.io/...
+     * Verify that connection is encrypted when set to true explicitly, makes a request to https://main.realtime.ably.net/...
      */
     public function testTLSExplicitTrue() {
         $opts = [
@@ -174,7 +176,7 @@ public function testTLSExplicitTrue() {
         ];
         $ably = new PubSubHttpClient( $opts );
         $ably->time(); // make a request
-        $this->assertMatchesRegularExpression( '/^https:\/\/rest\.ably\.io/', $ably->http->lastUrl, 'Unexpected scheme/url mismatch' );
+        $this->assertMatchesRegularExpression( '/^https:\/\/main\.realtime\.ably\.net/', $ably->http->lastUrl, 'Unexpected scheme/url mismatch' );
     }
 
 
@@ -214,9 +216,9 @@ public function testFallbackHosts() {
             $this->fail('Expected the request to fail');
         } catch(AblyRequestException $e) {
             $this->assertCount(6, $ably->http->visitedHosts);
-            $this->assertEquals( 'rest.ably.io' , $ably->http->visitedHosts[0],'Expected to try primary restHost first' );
+            $this->assertEquals( 'main.realtime.ably.net' , $ably->http->visitedHosts[0],'Expected to try primary domain first' );
 
-            $expectedFallbackHosts = array_merge( [ 'rest.ably.io' ], Defaults::$fallbackHosts );
+            $expectedFallbackHosts = array_merge( [ 'main.realtime.ably.net' ], Defaults::$fallbackHosts );
             $this->assertNotEquals( $expectedFallbackHosts, $ably->http->visitedHosts,'Expected to have fallback hosts randomized' );
 
             sort($expectedFallbackHosts);
@@ -227,15 +229,15 @@ public function testFallbackHosts() {
     }
 
     /**
-     * When using custom environment, should use custom env. fallback hosts
-     * @testdox RSC15b1,RSC15g2
+     * When using a routing policy endpoint, should use that endpoint's fallback hosts
+     * @testdox REC1b4, REC2c4
      */
-    public function testEnvFallbackHosts() {
+    public function testEndpointFallbackHosts() {
         $opts = [
             'key' => 'fake.key:veryFake',
             'httpClass' => 'tests\HttpMockInitTestTimeout',
             'httpMaxRetryCount' => 5,
-            'environment' => 'alpha'
+            'endpoint' => 'alpha'
         ];
         $ably = new PubSubHttpClient( $opts );
         try {
@@ -243,9 +245,9 @@ public function testEnvFallbackHosts() {
             $this->fail('Expected the request to fail');
         } catch(AblyRequestException $e) {
             $this->assertCount(6, $ably->http->visitedHosts);
-            $this->assertEquals( 'alpha-rest.ably.io' , $ably->http->visitedHosts[0],'Expected to try primary restHost first' );
+            $this->assertEquals( 'alpha.realtime.ably.net' , $ably->http->visitedHosts[0],'Expected to try primary domain first' );
 
-            $expectedFallbackHosts = array_merge( [ 'alpha-rest.ably.io' ], Defaults::getEnvironmentFallbackHosts('alpha'));
+            $expectedFallbackHosts = array_merge( [ 'alpha.realtime.ably.net' ], Defaults::getEndpointFallbackHosts('alpha'));
             $this->assertNotEquals( $expectedFallbackHosts, $ably->http->visitedHosts,'Expected to have fallback hosts randomized' );
 
             sort($expectedFallbackHosts);
@@ -263,7 +265,7 @@ public function testNoFallbackOnEmptyCustomFallbacks() {
         $opts = [
             'key' => 'fake.key:veryFake',
             'httpClass' => 'tests\HttpMockInitTestTimeout',
-            'restHost' => 'custom.host.com',
+            'endpoint' => 'custom.host.com',
             'fallbackHosts' => [],
         ];
         $ably = new PubSubHttpClient( $opts );
@@ -277,7 +279,7 @@ public function testNoFallbackOnEmptyCustomFallbacks() {
     }
 
     /**
-     * Verify that custom restHost and custom fallbackHosts are working
+     * Verify that a hostname endpoint and custom fallbackHosts are working
      * @testdox RSC15b2, RSC15g1
      */
     public function testCustomHostAndFallbacks() {
@@ -287,7 +289,7 @@ public function testCustomHostAndFallbacks() {
             'third-fallback.custom.com',
         ];
         $defaultOpts = new ClientOptions([
-            'restHost' => 'rest.custom.com',
+            'endpoint' => 'rest.custom.com',
             'fallbackHosts' => $customFallbacks,
         ]);
 
@@ -302,9 +304,9 @@ public function testCustomHostAndFallbacks() {
             $this->fail('Expected the request to fail');
         } catch(AblyRequestException $e) {
             $this->assertCount(4, $ably->http->visitedHosts);
-            $this->assertEquals( 'rest.custom.com' , $ably->http->visitedHosts[0],'Expected to try primary restHost first' );
+            $this->assertEquals( 'rest.custom.com' , $ably->http->visitedHosts[0],'Expected to try primary domain first' );
 
-            $expectedFallbackHosts = array_merge( [ $defaultOpts->restHost ], $customFallbacks);
+            $expectedFallbackHosts = array_merge( [ $defaultOpts->getPrimaryDomain() ], $customFallbacks);
             sort($expectedFallbackHosts);
             $actualVisitedHosts = $ably->http->visitedHosts; // copied by value;
             sort($actualVisitedHosts);
@@ -332,19 +334,20 @@ public function testNoFallbackOnClientError() {
             $this->fail('Expected the request to fail');
         } catch(AblyRequestException $e) {
             $this->assertCount(1, $ably->http->visitedHosts);
-            $this->assertEquals( [ 'rest.ably.io' ], $ably->http->visitedHosts, 'Expected to have tried only the default host' );
+            $this->assertEquals( [ 'main.realtime.ably.net' ], $ably->http->visitedHosts, 'Expected to have tried only the default host' );
         }
     }
 
     /**
-     * Verify that default fallback hosts are NOT used when using a custom host
-     * @testdox RSC15k
+     * Verify that default fallback hosts are NOT used with a hostname endpoint,
+     * so a qualifying error fails immediately
+     * @testdox RSC15k, REC2c2, RSC15m
      */
     public function testNoFallbackOnCustomHost() {
         $opts = [
             'key' => 'fake.key:veryFake',
             'httpClass' => 'tests\HttpMockInitTestTimeout',
-            'restHost' => 'custom.host.com',
+            'endpoint' => 'custom.host.com',
         ];
         $ably = new PubSubHttpClient( $opts );
         try {
@@ -385,7 +388,7 @@ public function testFallbackHostHeader() {
             'third-fallback.custom.com',
         ];
         $opts = new ClientOptions([
-            'restHost' => 'rest.custom.com',
+            'endpoint' => 'rest.custom.com',
             'fallbackHosts' => $customFallbacks,
             'key' => 'fake.key:veryFake',
             'httpClass' => 'tests\HttpMockInitTestTimeout'
@@ -412,35 +415,35 @@ public function testCachedFallback() {
             'key' => self::$testApp->getAppKeyDefault()->string,
             'fallbackRetryTimeout' => $fallbackCacheTimeoutInMs,
             'httpClass' => 'tests\HttpMockCachedFallback',
-            'restHost' => 'custom.host.com',
+            'endpoint' => 'custom.host.com',
             'fallbackHosts' => [
                 'fallback1',
-                'c.ably-realtime.com', // valid fallback host
+                'main.c.fallback.ably-realtime.com', // valid fallback host
                 'fallback2',
             ],
         ]));
 
         $ably->time();
-        $this->assertEquals("c.ably-realtime.com", $ably->host->getPreferredHost()); // check for cached host
+        $this->assertEquals("main.c.fallback.ably-realtime.com", $ably->host->getPreferredHost()); // check for cached host
         $this->assertGreaterThanOrEqual(1, $ably->http->fallbackRetries );
         $ably->http->resetRetries();
 
         $ably->time();
         $ably->time();
-        $this->assertEquals("c.ably-realtime.com", $ably->host->getPreferredHost()); // check for cached host
+        $this->assertEquals("main.c.fallback.ably-realtime.com", $ably->host->getPreferredHost()); // check for cached host
         $this->assertEquals( 0, $ably->http->fallbackRetries); // zero retries since cached fallback is used
 
         sleep( 2); // expire cached host
 
         $ably->time();
-        $this->assertEquals("c.ably-realtime.com", $ably->host->getPreferredHost()); // check for cached host
+        $this->assertEquals("main.c.fallback.ably-realtime.com", $ably->host->getPreferredHost()); // check for cached host
         $this->assertGreaterThanOrEqual( 1, $ably->http->fallbackRetries );
     }
 
     /**
      * Verify accuracy of time (to within 2 seconds of actual time)
      *
-     * RSC16 PubSubHttpClient#time function sends a get request to rest.ably.io/time
+     * RSC16 PubSubHttpClient#time function sends a get request to main.realtime.ably.net/time
      * and returns the server time in milliseconds since epoch
      */
     public function testTimeAndAccuracy() {
@@ -475,7 +478,7 @@ public function testActiveInternetConnection() {
     public function testTimeFailsWithInvalidHost() {
         $ablyInvalidHost = new PubSubHttpClient( [
             'key' => 'fake.key:veryFake',
-            'restHost' => 'this.host.does.not.exist',
+            'endpoint' => 'this.host.does.not.exist',
         ]);
 
         $this->expectException(AblyRequestException::class);
@@ -496,10 +499,10 @@ public function testHttpTimeout() {
             'httpRequestTimeout' => 20, // 20 ms
         ]);
 
-        $ably->http->get('https://rest.ably.io/time'); // should work
+        $ably->http->get('https://main.realtime.ably.net/time'); // should work
         $this->expectException(AblyRequestException::class);
         $this->expectExceptionCode(50003);
-        $ablyTimeout->http->get('https://rest.ably.io/time'); // guaranteed to take more than 20 ms
+        $ablyTimeout->http->get('https://main.realtime.ably.net/time'); // guaranteed to take more than 20 ms
     }
 }
 
@@ -564,7 +567,7 @@ public function __construct( $clientOptions ) {
     }
 
     public function request( $method, $url, $headers = [], $params = [] ) {
-        if ( parse_url($url, PHP_URL_HOST) == "c.ably-realtime.com" ) { // cache specific host
+        if ( parse_url($url, PHP_URL_HOST) == "main.c.fallback.ably-realtime.com" ) { // cache specific host
             return parent::request($method, $url, $headers, $params);
         }
         $this->fallbackRetries++;
diff --git a/tests/TypesTest.php b/tests/TypesTest.php
index ec3196f..0d28c6a 100644
--- a/tests/TypesTest.php
+++ b/tests/TypesTest.php
@@ -141,8 +141,7 @@ public function testClientOptionsType() {
             'authHeaders',
             'authParams',
             'queryTime',
-            'environment',
-            'restHost',
+            'endpoint',
             'port',
             'tlsPort',
             'httpOpenTimeout',
diff --git a/tests/factories/TestApp.php b/tests/factories/TestApp.php
index 67332f4..c6ccdc0 100644
--- a/tests/factories/TestApp.php
+++ b/tests/factories/TestApp.php
@@ -25,7 +25,7 @@ public function __construct() {
 
         $settings = [];
 
-        $settings['environment'] = getenv( 'ABLY_ENV' ) ? : 'sandbox';
+        $settings['endpoint'] = getenv( 'ABLY_ENDPOINT' ) ? : 'nonprod:sandbox';
         $settings['useBinaryProtocol'] = getenv('PROTOCOL') !== 'json';
         //$settings['logLevel'] = Log::DEBUG;
 
@@ -33,7 +33,7 @@ public function __construct() {
 
         $this->options = $settings;
 
-        $this->server = $clientOpts->getHostUrl($clientOpts->getPrimaryRestHost());
+        $this->server = $clientOpts->getHostUrl($clientOpts->getPrimaryDomain());
         $this->init();
 
         return $this;