moved to a new flat. local cable ISP:
need to pay for TV, too (I dont have a TV): 9,90€
now I have to find out if my router is bugged or the ISP's service. the ISP locks the MAC adress of the device conencted to the modem. as I cant get my router to find the internet connection, I plugged my desktop PC directly into the mdoem and faked the MAC adress of my router .. voila. works.
still I need to get it working corretly to set up a home lan..