GL-E750V2 eSIM Profile activation fails

Hi,

I'm having a problem activating an additional eSIM profile on my Mudi (GL-E750V2). I bought the EIOTClub SIM to eSIM card but when I try to add an additional profile (directly after I add the QR code) it fails with the following error:

Device start connect internet
Connect internet fail: Please make sure that you have set up the Internet interface to use cellular (with esim seed profile), wan cable or repeater to connect to the Internet.

The device has an internet connection via cellular but I tried adding an USB Ethernet Adaper as well, without success. Is there anything I might have missed?
I followed the steps from the official glinet docs from their website. The firmware is up to date. If it helps I can add the exact version later.