New backend. How to connect?

I assume ttnctl subscribe gives you no errors?

For MQTT clients, the following works well for me in MQTT.fx, MQTTLens and Paho's MQTT RCP Application. Not all clients require all settings:

• Broker address: tcp://staging.thethingsnetwork.org
  • In MQTT.fx and MQTTLens, only enter staging.thethingsnetwork.org
  • TTN does not support WebSockets, ws://
• Port: 1883
  • In Paho, add it to the address, so: tcp://staging.thethingsnetwork.org:1883
• SSL/TLS: no
• Client ID: generate a random value (not important for QoS 0)
• Username/password: EUI and Access Keys from ttnctl applications
• Clean Session: enabled
• MQTT Version: default
• Quality of Service, QoS: 0
• Topic: # for all topics, or something more specific such as +/devices/+/up

It's still available, but: it's unfortunately down at the moment. If all is well it will come back though. But it won't be available when TTN goes live, early July.