I wanted to close this thread in case in the future someone had a similar problem, and to thank the contributors. Using a borrowed Draytek 2860 (which is in effect the later model, the web browser is earily similar) with the settings you suggested it connected with no problem. Hence I have concluded that the 2850 is faulty. I guess that if anything will fail it will be the VDSL input, exposed to the dangerous outside world with all sorts of electrical surges.
Regards
