Come into work this morning to find the estate had no power (went off at 6:40), my computer kept logging stats for around 32 minutes before shutting down at 07:12. I then powered it up for a few minutes at 07:44. Unfortunately I turned it off again about a minute before the power came back. The modem stayed powered up throughout as that's on a larger UPS round the main office.
Anyway the line stats show quite a difference, interleaved attainable went to 53,892Kbps briefly before leveling off at 47,688Kbps then dropping back to 41520 when the power came back 07:52. SNRM peaked at 13.2db dropping to 9.9db and returning to 6.4db when power came back.
FEC errors dropped from around 480,000 to nothing for the duration, apart from a couple of very small errors, so I guess that tells me that it is electrical noise interference that affects our line a lot.
Username on MDWS is Ronskiwork if any one want's to take a look.