I am not able to connect to thethingsnetwork (TTN) using MQTT by setting the “Lora Gateway” options. I can only use UDP of semtech to connect, yet I have read it is not as secure as using MQTT with TLS.
I believe this is not possible as TTN is not a free service after all. If you want to use it as the community network, you only have the option to connect via the packet forwarder. If you need to use the MQTT Bridge you will need to have your own MQTT Broker and LoRa Network server.