Install custom router for telekom

I use my tp-link router Archer C80

Select connection type

You will need to select the PPPoE connection type
PPPoE connection type

Provide username and password

Template of username is: <Anschlusskennung><Zugangsnummer><Mitbenutzernummer> NOTE: symbols <, > do not need to add
Template password: Persönliche Kennwort
You can find Anschlusskennung, Zugangsnummer, Mitbenutzernummer, and Persönliche Kennwort in your contract

Additional settings [for me it was a game changer]

I had to select the special ISP Settings (IPTV/VLAN) with a profile for Telekom
Special ISP settings