I have read that Christmas lights can be a potent source of REIN, and suspect that I may have been a victim this season.
My 1km-ish line (Huawei modem & DSLAM) has generally been reasonably stable, with one period of 50 days without a resync last autumn (see attached modem logfile). However, in the run-up to Christmas it suffered frequent short bursts of errors and associated resyncs. Eventually DLM reacted by increasing interleaving from 700-ish to over 2000, with INP going from 3 to 8.5 and delay from 8 to 16. This successfully stabilised the line, but at the price of a drop in DS sync speed from 40000 to 32750.
Over this period a house across the road was sporting a garish array of flashing lights all over its front wall. These were ripped down on Boxing Day, and after that the error rates and dips in attainable rate seemed to reduce. 8 days later there was another on-the-fly resync and DLM restored the line parameters to the previous values.
This does seem to be a coincidence if not cause and effect, but I am puzzled why the lights, which were flashing 24/7, should have caused only occasional bursts of errors rather than a continual high level of noise. In any event DLM, left to get on with it, seemed pretty effective in "making the best of a bad job".
On-going stats of the period in question attached, unfortunately with some gaps. Also current stats both before and after the most recent resync.