I am still struggling to receive MQTT traffic from Cerbo after Venus OS 3.21 upgrade using mqtt Explorer addon in Home Assistant.
MQTT Explorer message is "disconnected from server". Port 1883 is used. Obviously a role back to 3.14 is working.
In mqtt Explorer I used all kind of Ports, included a User Name, Password and switched encryption and/or validate certificate leading to a ECONNREFUSED message.