After 108 hours 3.543 - -21.2 still going strong 

I have noticed several times every day that the mcModule is not sending the MQTT message to the mcGateway and misses a couple of minutes and every time I could see that the voltage has a drop, so something strange is happening on the mcModule.
Almost every time when the issue occurs then I could see that the mcModule is sending multiple messages from its queue but sometimes not? maybe the queue could be filled with something else and the messages gets lost?