Also check if connection to the MQTT server is still established during topic subscription and request of last values. Otherwise it can happen that the connection is ripped out under you and you won't even notice.

Author: aentinger

src/ArduinoIoTCloudTCP.cpp

@@ -328,6 +328,14 @@ ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_ConnectMqttBroker()
 
 ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_SubscribeMqttTopics()
 {
+  if (!_mqttClient.connected())
+  {
+    DEBUG_ERROR("ArduinoIoTCloudTCP::%s MQTT client connection lost", __FUNCTION__);
+    _mqttClient.stop();
+    execCloudEventCallback(ArduinoIoTCloudEvent::DISCONNECT);
+    return State::ConnectPhy;
+  }
+
   if (!_mqttClient.subscribe(_dataTopicIn))
   {
     DEBUG_ERROR("ArduinoIoTCloudTCP::%s could not subscribe to %s", __FUNCTION__, _dataTopicIn.c_str());
@@ -360,6 +368,14 @@ ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_SubscribeMqttTopics()
 
 ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_RequestLastValues()
 {
+  if (!_mqttClient.connected())
+  {
+    DEBUG_ERROR("ArduinoIoTCloudTCP::%s MQTT client connection lost", __FUNCTION__);
+    _mqttClient.stop();
+    execCloudEventCallback(ArduinoIoTCloudEvent::DISCONNECT);
+    return State::ConnectPhy;
+  }
+
   /* Check whether or not we need to send a new request. */
   unsigned long const now = millis();
   if ((now - _lastSyncRequestTickTime) > TIMEOUT_FOR_LASTVALUES_SYNC)