I would try to monitor the length of the output queue. See _io_thread_func in MQTTMsgHandler.py - in there there's the transmit loop and you could add some signaling there to indicate the TX queue is empty. You'll probably need to modify the code and rename the function so you are not using the builtin frozen ones.

@randomrnti Figured out my issue was due to the AWS policy only allowing certain clients for the iot:Connect policy. Changing it to the wildcard * fixed my issue. Another issue though is I can only get it working for Wifi. The moment I attempt this on NB-IoT I'm getting the following errors: AWSIoTMQTTClient Socket create error: [Errno -78] MBEDTLS_ERR_NET_SEND_FAILED simple.py Traceback (most recent call last): File "main.py", line 90, in <module> File "main.py", line 79, in run File "/flash/lib/simple.py", line 56, in connect OSError: [Errno 113] ECONNABORTED This again is on the connect action and I've tried with connecting using both the IP Address and it's domain name.

@matt3526 Thingsboard has nice documented tracking use-case: https://thingsboard.io/fleet-tracking/

@reidfo Sure looks like it. Change line 294, see if you get a different behavior. http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc385349238 https://github.com/pycom/pycom-micropython-sigfox/blob/f517b1df5083ddc158c075852d7f2497480b0d84/esp32/frozen/Common/MQTTClient.py#L294

... forgot duplicate CLIENT_ID in config.py... Problem solved!