Mr sdf,
If anything wrong with your connection, you should call Telekom instead. All connections is done by Telekom, while TMnut they only detect the signal, username and password.
Or maybe something is wrong with the telephone line, is it old? some old lines they have problem receiving full bandwidth, or is the line too long?
Long line - frequent disconnected and hard to receive broadband signal.
Old & long line - once thunder lightning kaboom, straight away disconnected, and the broadband signal line blinking non stop.
Mine is a new line, and the line is very short connect from the pole to my room. My bandwidth always maintain at 48 - 50 KB/s.