String "Command received: " not shown on the serial monitor output

There are a couple of things I would try:

  • Try increasing the packet size on the underlying pubsubclient: Sending commands with larger payloads Unfortunately the underlying library silently refuses commands if the packet is too large.

  • Does the command show up in the application communication log? This log is a live stream of all device communication. Open it another tab and then attempt to send the command. It should show up.

  • Try manually sending the command using the debug tab on the device page.