@stefan-de-lange thank you for pointing me in this direction. I will read up and try to make it work using this manual.

I am currently working with a device which is NB-IoT capable but only has the capability to send data throught MQTT.
Is it possible to use this device in combination with a broker at the t-mobile end?
The device I am using is a Vega SH2. The only settings I am able to make for NB-IoT connection are show below.

The device does get a connection to the NB-IoT network and gets an IP address assigned. But then connecting to the MQTT broker fails.

Could someone help me out with the correct MQTT settings to make?