@alexbenisch hi, not sure if I'll be able to help, don't know anything about that particular modem, but one thing to check would be to run mmcli (ModemManager) to see what that says.
Make sure ModemManager is running and sees the modem, and the modem should be in the "connected" state. Probably it is not "connected" in your case.
You also have a SIM card plugged in somehow? Maybe check that the sim card is okay by putting it in some other phone or so, to test that separately?
1/2
@eliasr checking the sim is worth a try, connection state too. great thanks, enjoy your Sunday.
@alexbenisch
Also: does the sim card need a pin code before it can work, and if so, do you have a method to enter the pin code? It can be done via mmcli I think.
My understanding of how these things work is that the modem should exist as a device in the Linux kernel, then ModemManager talks to that, and finally NetworkManager can handle that network connection for you. So both mmcli and nmcli can be of interest. ModemManager has a debug mode you can try.
Anyway, good luck with it 🙂
2/2