Port 39501 is where you direct incoming HTTP messages to the hub from your device. The device ID must be one of three things, i know one is the MAC. The other two escape me right now but if you have a device sending info to the hub that the hub doesn't know what to do with, you will see an entry in the logs with the three ways that device is being identified by the Hub. Then the message is automatically parsed to the correct device in your hub. This is the basis of the Hubduino project. This is how all those sensor inputs are passed back to Hubitat from your ESP board. This is also how @ericm's tasmota firmware passes the switch state back to the hub.
Download the Hubitat app
