[lwde]

You have the right to router freedom even with FTTH. And fortunately, with DTAG FTTH, you can also book 1und1 with good peering (:

[madduci]

router freedom yes, but the Telekom Black Box that takes as input the Fiber cable is still a real "black box" that needs to be installed

[Fnoord]

Here in NL I've been able to replace router (Zyxel in my case) and ONT (Huawei in my case) with one SFP+ (went with some South-Korean one). Only had to register the serial of my SFP+.

[lwde]

nope, just remove the Telekom Black Box/ONT and get a GPON SFP (Like Luleey or FS) and register that mac.