It does not support set username and PWD in the MQTT setting now.
It only supports connecting the MQTT server in an anonymous mode. The authentication mode is like a clientID way(include the SN in the topic).
The MQTT feature in the energy meter is not complete now. (because it is not the default uploading method in IAMMETER-cloud).
we have planned to provide more MQTT functions in later upgrading(support some simple authentification mode,such as username and password, support tls mode)