Personally I would have reservations here. We’ve not see recent router stats - data speed tests are one thing router stats are real measures as to what is happening on the line.
I suspect that the SNRM has been raised to maintain stability during unidentified transient events, leading to and overall reduction in speed.
When tested, no fault was found - that could mask the presence of an intermittent fault - wet joints - or other issues which appear when there’s a call on the line. Such issues are not going to be identified in the absence of a (cheap) handset. I’d keep a watch on this, especially during inclement weather.
Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.
