After looking for alternatves to the suggested Router from Telekom (AVM FritzBox and HUawei Speedport), I've discovered the possibility of configuring my existing OpenWRT Router to act as gateway to the Telekom FTTH (Fiber To The Home) Magenta Zuhause package.
The WAN interface must be configured as follows (see your Telekom letter):
- Protocol:
PPPoE - PAP/CHAP username: