There's no sign that these temporary SNRM drops are leading to large increases in CRCs and errored seconds, and they're not causing resyncs, so I doubt that DLM is even aware of them. They won't be responsible for your continued banding.
The SNRM drops are obviously not desirable, but finding their cause is going to be a bit of a needle in a haystack exercise. Can you possibly relate them to some electrical activity in your home at the same times? Are you on good enough terms with your neighbours to ask them the same question?
