Hi there! Yeah I registered the MQTT device via ThingSpeak. I used the MQTT Explorer you suggested and I was able to post some data to Thingspeak by typing literal values into the Explorer. This leads me to think that it’s an issue with the Mayfly code.
@neilh20 I’m curious as to how you set up the ThingSpeak using POST. I’m not really committed to the MQTT platform, and I’m curious how you set your’s up.