I've had FTTC for about 5 months now. My line is about 1800m to the cabinet and I had a rock solid sync of around 20Mb until about 3 weeks ago. Then the SNR started fluctuating wildly and the broadband dropped out about every 10 minutes. There was also a lot of noise on the line so my ISP (Zen) reported it to Openreach as a voice fault.
It took several attempts but eventually a bad joint was found and the voice side was fixed. But Zen told me that there was still a fault on the line (Battery) and after another 2 visits, part of my line was swapped to another pair and the fault was finally cleared. In the process my downstream attenuation increased to 29.7dB (was previously 27.8).
But the problem I have now is that I am only syncing at 13Mb down / 797kb up but the margins are 12dB down / 20dB up. I have asked Zen if the DLM was reset after BT fixed the fault but they are adamant that 13Mb is all that my line is now capable of and that it would need to fall below 11Mb before BT would consider it to be a fault.
So my question is, does this sound like DLM has not been reset and I just need to wait for it to recover - or has something else been changed to throttle my speed in order to make it more stable?