The Version 2.2 software for the WiFi Wireless Gateway now has a built in MQTT Client that can publish sensor messages to an MQTT Broker.
The Gateway can connect to a Broker with or without credentials .
The Gateway will publish to the broker using the Gateway Name as the primary subscription and the sensor name and type as the sub-subscription.
I have tested it on a local Mosquitto Broker with no credentials, and two Internet Brokers. One built with a Mosquitto Docker container and the second being the Emqx.io public Broker. Both of the Internet Brokers required credentials.
Glenn