fixed

netty-mqtt/src/main/java/org/thingsboard/mqtt/MqttClientImpl.java

@@ -456,16 +456,25 @@ final class MqttClientImpl implements MqttClient {
 
     @Override
     public void disconnect() {
+        if (disconnected) {
+            return;
+        }
+
         log.trace("[{}] Disconnecting from server", channel != null ? channel.id() : "UNKNOWN");
-        disconnected = true;
         if (this.channel != null) {
             MqttMessage message = new MqttMessage(new MqttFixedHeader(MqttMessageType.DISCONNECT, false, MqttQoS.AT_MOST_ONCE, false, 0));
-            ChannelFuture channelFuture = this.sendAndFlushPacket(message);
+
+            sendAndFlushPacket(message).addListener((ChannelFutureListener) future -> {
+                future.channel().close();
+                disconnected = true;
+            });
+
             eventLoop.schedule(() -> {
                 if (channel.isOpen()) {
                     this.channel.close();
+                    disconnected = true;
                 }
-            }, 500, TimeUnit.MILLISECONDS);
+            }, 1, TimeUnit.SECONDS);
         }
     }
 

netty-mqtt/src/test/java/org/thingsboard/mqtt/MqttClientTest.java

@@ -119,6 +119,36 @@ class MqttClientTest {
         assertThat(client.isConnected()).isTrue();
     }
 
+    @Test
+    void testDisconnectFromBroker() {
+        // GIVEN
+        var clientConfig = new MqttClientConfig();
+        clientConfig.setOwnerId("Test[ConnectToBroker]");
+        clientConfig.setClientId("connect");
+
+        client = MqttClient.create(clientConfig, null, handlerExecutor);
+
+        // WHEN
+        Promise<MqttConnectResult> connectFuture = client.connect(broker.getHost(), broker.getMqttPort());
+
+        // THEN
+        assertThat(connectFuture).isNotNull();
+
+        Awaitility.await("waiting for client to connect")
+                .atMost(Duration.ofSeconds(10L))
+                .until(connectFuture::isDone);
+
+        assertThat(connectFuture.isSuccess()).isTrue();
+
+        // WHEN
+        client.disconnect();
+
+        // THEN
+        Awaitility.await("waiting for client to disconnect")
+                .atMost(Duration.ofSeconds(5))
+                .untilAsserted(() -> assertThat(client.isConnected()).isFalse());
+    }
+
     @Test
     void testDisconnectDueToKeepAliveIfNoActivity() {
         // GIVEN