You've every right to feel smug... full stats are at the end of the post. :-)
j0hn sets mode to +smug So you have a noise source that comes on briefly, and knocks the actual SNRM down by 3dB.
In the 2 examples you posted it lasted about 1 min and about 5 minutes in the 2nd example.
Then about 70-75 mins later it triggers a resync, and the 3dB noise is present during the resync/training causing you to sync 3dB lower than the target SNRM.
The strange thing is it looks like this noise source is gone by the time DslStats does the first sample after sync is achieved. The actual SNRM immediately has 3dB "spare".
Very very strange indeed.
Are you still on the HG612? I wonder if it could be a problem with the modem. Might be a good time to try that Zyxel modem!
What you could do is set a email alert in DslStats to email you if the downstream SNRM drops below x.
As you're at 6dB I would set it to about 4dB.
It will email you 70-75 minutes before the resync will come when the SNRM drops for the brief period.
If this carries on will DLM get to the point that it aborts 3dB completely on this line?
Do you get a burst of ES or LEFTERS during the brief SNRM crash?
DLM is unlikely to take action on the line for a single resync every few days.
You could either take the line down for 10 minutes at around 70 minutes after DslStats emails you, though not ideal.
It should also be safe to resync the line after it comes back up at 6dB. DLM won't take action on that if it's the only resync that day. Again that's not ideal.
Does anyone else have any opinions on what could cause SNRM to drop by 3dB for 1-5 mins, then 70-75 minutes later it causes the line to resync, coming back up 3dB higher than the target SNRM?