This is an update to my earlier post.

I have seen a sudden increase in speed and the noise margins are now significantly lower. I do not know why. I will monitor the situation very carefully and make sure that the now acceptable levels are maintained. Hopefully I will not need to post here again about the same issue any time soon.

Thanks to everyone who answered my original post. Enjoy your holidays.

- David

That would be the automatic reduction of target noise margin once system detects what it thinks is a line with less errors/noise.

Usually takes two weeks, but a lot of changes of late, so it may be faster now