diff --git a/.ci/ubuntu/gha-setup.sh b/.ci/ubuntu/gha-setup.sh
index 73cc741bb..ab66c49c9 100755
--- a/.ci/ubuntu/gha-setup.sh
+++ b/.ci/ubuntu/gha-setup.sh
@@ -54,6 +54,7 @@ function start_toxiproxy
         docker run --detach $docker_pull_args \
             --name "$toxiproxy_docker_name" \
             --hostname "$toxiproxy_docker_name" \
+            --add-host=host.docker.internal:host-gateway \
             --publish 8474:8474 \
             --publish 5673:5673 \
             --network "$docker_network_name" \
@@ -133,3 +134,7 @@ start_rabbitmq
 wait_rabbitmq
 
 get_rabbitmq_id
+
+export TOXIPROXY_HOST="${TOXIPROXY_HOST:-localhost}"
+export TOXIPROXY_AMQP_TARGET="${TOXIPROXY_AMQP_TARGET:-host.docker.internal}"
+export TOXIPROXY_AMQP_PORT="${TOXIPROXY_AMQP_PORT:-5673}"
diff --git a/.ci/ubuntu/rabbitmq.conf b/.ci/ubuntu/rabbitmq.conf
index 64ed2d30e..66050d70f 100644
--- a/.ci/ubuntu/rabbitmq.conf
+++ b/.ci/ubuntu/rabbitmq.conf
@@ -24,3 +24,7 @@ ssl_options.fail_if_no_peer_cert = false
 management.ssl.certfile   = /etc/rabbitmq/certs/server_certificate.pem
 management.ssl.keyfile    = /etc/rabbitmq/certs/server_key.pem
 management.ssl.cacertfile = /etc/rabbitmq/certs/ca_certificate.pem
+
+# RabbitMQ 4.x blocks transient non-exclusive queues by default; the test suite
+# still declares queues with the AMQP defaults (non-durable, non-exclusive).
+deprecated_features.permit.transient_nonexcl_queues = true
diff --git a/.github/workflows/phpunit.yml b/.github/workflows/phpunit.yml
index cc4d5f6c5..b548736c8 100644
--- a/.github/workflows/phpunit.yml
+++ b/.github/workflows/phpunit.yml
@@ -44,7 +44,7 @@ jobs:
     name: PHP ${{ matrix.php }} + phpseclib ${{ matrix.phpseclib }}
     env:
       TOXIPROXY_HOST: localhost
-      TOXIPROXY_AMQP_TARGET: php-amqplib-rabbitmq
+      TOXIPROXY_AMQP_TARGET: host.docker.internal
       TOXIPROXY_AMQP_PORT: 5673
     steps:
     - name: Checkout
diff --git a/tests/Functional/AbstractConnectionTest.php b/tests/Functional/AbstractConnectionTest.php
index 218c49a30..9d6d573d1 100644
--- a/tests/Functional/AbstractConnectionTest.php
+++ b/tests/Functional/AbstractConnectionTest.php
@@ -113,7 +113,7 @@ protected function get_toxiproxy_amqp_port()
             $this->markTestSkipped('TOXIPROXY_AMQP_PORT is not set');
         }
 
-        return $port;
+        return (int) $port;
     }
 
     protected function assertConnectionClosed(AbstractConnection $connection)
diff --git a/tests/Functional/Connection/ConnectionAuthTest.php b/tests/Functional/Connection/ConnectionAuthTest.php
index 15958afc7..5e8159c55 100644
--- a/tests/Functional/Connection/ConnectionAuthTest.php
+++ b/tests/Functional/Connection/ConnectionAuthTest.php
@@ -67,7 +67,7 @@ private function createUser($username, $password)
         $userEndpoint = $this->getManagementBase() . 'api/users/' . $username;
         $passwordHash = '';
         if (!empty($password)) {
-            $salt = substr(md5(mt_rand()), 0, 4);
+            $salt = substr(md5((string) mt_rand()), 0, 4);
             $passwordHash = base64_encode($salt . hash('sha256', $salt . $password, true));
         }
         $request = Request::put(
diff --git a/tests/Functional/ToxiProxy.php b/tests/Functional/ToxiProxy.php
index 83f338e52..318bb8d5d 100644
--- a/tests/Functional/ToxiProxy.php
+++ b/tests/Functional/ToxiProxy.php
@@ -49,6 +49,8 @@ public function __destruct()
      */
     public function open($host, $port, $listen)
     {
+        $this->closeIfExists();
+
         $payload = [
             'name' => $this->name,
             'upstream' => $host . ':' . $port,
@@ -56,13 +58,13 @@ public function open($host, $port, $listen)
         ];
         $url = $this->api . '/proxies';
         $request = Request::post($url, json_encode($payload), 'json');
-        $request->timeout(1);
+        $request->timeout(5);
         $request->expectsJson();
         $response = $request->send();
         if ($response->code !== 201) {
             throw new \RuntimeException('Cannot create Toxiproxy connection');
         }
-        $this->listen = $listen;
+        $this->listen = (int) $listen;
         $this->isOpen = true;
     }
 
@@ -85,7 +87,7 @@ public function mode($type, $attributes = [], $direction = 'upstream', $toxicity
         ];
         $url = sprintf('%s/proxies/%s/toxics', $this->api, $this->name);
         $request = Request::post($url, json_encode($payload), 'json');
-        $request->timeout(1);
+        $request->timeout(5);
         $request->expectsJson();
         $response = $request->send();
 
@@ -94,6 +96,17 @@ public function mode($type, $attributes = [], $direction = 'upstream', $toxicity
         }
     }
 
+    private function closeIfExists()
+    {
+        $url = sprintf('%s/proxies/%s', $this->api, $this->name);
+        $request = Request::delete($url);
+        $request->timeout(5);
+        try {
+            $request->send();
+        } catch (\Exception $exception) {
+        }
+    }
+
     /**
      * Disable(block) proxy connection so no data can be transferred.
      * @throws \Httpful\Exception\ConnectionErrorException
@@ -113,10 +126,22 @@ public function disable()
      */
     public function close()
     {
+        if (!$this->isOpen) {
+            return;
+        }
+
         $url = sprintf('%s/proxies/%s', $this->api, $this->name);
-        $response = Request::delete($url)->send();
-        if ($response->code !== 204 && $response->code !== 404) {
-            throw new \RuntimeException('Cannot close Toxiproxy connection');
+        $request = Request::delete($url);
+        $request->timeout(5);
+        try {
+            $response = $request->send();
+            if ($response->code !== 204 && $response->code !== 404) {
+                throw new \RuntimeException('Cannot close Toxiproxy connection');
+            }
+        } catch (\Exception $exception) {
+            // Best-effort cleanup; a stale proxy is removed before the next open().
+        } finally {
+            $this->isOpen = false;
         }
     }
 
diff --git a/tests/config.php b/tests/config.php
index 1ba5c8c23..0086636e7 100644
--- a/tests/config.php
+++ b/tests/config.php
@@ -4,7 +4,7 @@
 
 define('HOST', getenv('TEST_RABBITMQ_HOST') ? getenv('TEST_RABBITMQ_HOST') : 'localhost');
 define('HOST6', getenv('TEST_RABBITMQ_HOST6') ? getenv('TEST_RABBITMQ_HOST6') : '[::1]');
-define('PORT', getenv('TEST_RABBITMQ_PORT') ? getenv('TEST_RABBITMQ_PORT') : 5672);
+define('PORT', (int)(getenv('TEST_RABBITMQ_PORT') ?: 5672));
 define('USER', getenv('TEST_RABBITMQ_USER') ? getenv('TEST_RABBITMQ_USER') : 'guest');
 define('PASS', getenv('TEST_RABBITMQ_PASS') ? getenv('TEST_RABBITMQ_PASS') : 'guest');
 define('VHOST', '/');