Well, that sounds interesting, maybe you need call TPLink support in Germany.

Hi Falconne It seems TPLink offer a beta firmware for this issue. You could ask their support for that firmware. Firmware 170407. There are several posts taking about this .

How about the WiFi button?Push it and seem what will happen.

There are two root Annex type in VDSL technology, Annex A and Annex B It seems TPLink in Germany sell VDSL Annex B modem while they also sell normal VDSL Annex A modem which is the same as UK...

Annex M is a updated version of Annex A. Set Automatic should let your router work at Annex A mode and receive a internet though may be with a little speed down. So if you set it only work at Annex M...

Like a wireless AP? Disable DHCP maybe OK.But at that time you should make sure you have another router and you need to link LAN port