sounds like job for TM and/or the developer of your housing unit. in my case my SNR is good but line attenuation is about 36..I told was due to distance to DSLAM and/or copper line quality.

as mentioned in this thread http://forum.lowyat.net/topic/166678

"SNR 15 and below = Very FREQUENT disconnections. You should consult telekom to have your line checked, most cases are because the line are too old and once they are changed they're fine (the lines on the telephone poles). If you're using a lightning surge protector. REMOVE it. they are known to weaken the signal by around 50-70% in order to prevent the surge on devices."