What has happened to my connection - not a complaint

[#1]

After a brief power cut yesterday (lightning) the router resync'd at 3762kbps which is only a bit lower than normal with a 6dB default noise margin
Switched on the computer this morning and saw the noise margin - what the heck I thought
Sync still the same and no loss reported but look what has happened to the reported noise margin

[#2]

I thought your line was generally under performing anyway? In that your sync speed is lower than mine but my line attenuation is higher than yours (and I have old star wiring and no modern master socket).
I suppose it's remotely possible that some source of noise that's been continuously running for a long time suddenly got switched off.

[#3]

A while ago - over a year - I was getting about 4,800kbps but with major instability problems with the upload to the extent that uncapping it was a disaster
During an engineer visit - he was really good - he said that the three main feeders to the cab were not very good and that he switched me to the one which didn't give serious upstream errors when the phone rang. That was certainly a big improvement and I was happy with the result despite the big drop in download speed
I will do nothing for a few days to see if whatever was causing the problem remains fixed/switched off.

[#4]

Jim,
Its difficult to comment soundly based solely on that graph...
1. There is no corresponding synch speed data - on the right click context menu for this graph is there the option to overlay the DS synch speed?
2. The gap in the plotted time line obscures the characteristic of the SNRM shift - when it happened and how it happened.
It would be interesting to do a resynch and see what speed / SNRM you get.  Does rather make one wonder if you've been blighted with constant rein all this time?
Kevin

[#5]

As I said in the opening post the sync is unchanged at 3762kbps
The gap is because I don't leave the computer running over night which is when it happened
I don't want to do a resync until at least the early part of next week as it may be that whatever was causing the problem has been shut down over the weekend
Looking at the bit loading graph I am getting significantly higher noise margin per tone starting at about tone 84 and runs pretty much up to the highest tones in use

[#6]

Update
Just had another power cut - short blip
Speed now 3894kbps with a 6.1dB noise margin
So must put it down to one of those things