Apparently the GSM modem is unhappy if there are filesystem ops originating from the OTA code part during establishment of connections, pulling OTA code at the very front up update solves this problem

Author: aentinger

src/ArduinoIoTCloudTCP.cpp

@@ -166,6 +166,15 @@ int ArduinoIoTCloudTCP::begin(String brokerAddress, uint16_t brokerPort)
 
 void ArduinoIoTCloudTCP::update()
 {
+#if OTA_ENABLED
+    /* If a _ota_logic object has been instantiated then we are spinning its
+     * 'update' method here in order to process incoming data and generally
+     * to transition to the OTA logic update states.
+     */
+    OTAError const err = _ota_logic.update();
+    _ota_error = static_cast<int>(err);
+#endif /* OTA_ENABLED */
+
   /* Run through the state machine. */
   State next_state = _state;
   switch (_state)
@@ -180,17 +189,9 @@ void ArduinoIoTCloudTCP::update()
   _state = next_state;
 
   /* Check for new data from the MQTT client. */
-  if (_mqttClient.connected())
-    _mqttClient.poll();
-
-#if OTA_ENABLED
-    /* If a _ota_logic object has been instantiated then we are spinning its
-     * 'update' method here in order to process incoming data and generally
-     * to transition to the OTA logic update states.
-     */
-    OTAError const err = _ota_logic.update();
-    _ota_error = static_cast<int>(err);
-#endif /* OTA_ENABLED */
+  if ((_state == State::SubscribeMqttTopics) || (_state == State::RequestLastValues) || (_state == State::Connected))
+    if (_mqttClient.connected())
+      _mqttClient.poll();
 }
 
 int ArduinoIoTCloudTCP::connected()