No data on MQTT when deploying TTN v3.2.6

I have installed TTN v3.2.6 on a public IP. Everything seems to work except that i get no data to mqtt.
The same setup works when running on the public TTN-server. I can see my payload in the web-gui (sent from my end-device). How can i solve this ?
The MQTT-client connects ok (but no data is sent).

best regards, Magnus

Are you certain that you configured your mqtt client to listen on the right topic?

Yes. I got it working by enabling MQTT using the CLI. It did not work when i used the GUI.

Now there is another problem. Not all devices are able to join my network. This worked when i used TTN:s server (same devices and gateway). How can i debug that ?