I'm certainly learning something about the problem by running routerstats. DLM has increased my target noise margin to 12 dB
so my attempt to avoid this by getting in first with a DMT tweak didn't work. Now, most of the time my noise margin is between 10 and 12 dB, but occasionally there is a horrible pulse of interference from somewhere, as you can see below. I'm suspicious of my central heating thermostat, but haven't yet been able to nail it firmly to that source.
By the way, I think this is quite separate from the general problem which started 3 days ago - that seems to be settling down, with only a small variation in noise margin where it was hopping up and down by 6 dB every few seconds a couple of days ago.
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