TT-NW -hints

About APN:

With http://telekom.de SIM cards, you need to set the APN settings manually, this is what caused the issue.

You can find the correct APN settings following this link: https://www.telekom.de/hilfe/mobilfunk-mobiles-internet/mobiles-internet-e-mail/apn-mobilfunk/wie-lauten-die-apn-fuer-mobilfunk?samChecked=true