Here we go again; lightning strike 7 miles away and the four lines blipped and resynched at around 1620 UTC. I was asleep at the time they resynched and then we heard thunder and pulled the modem cables from the wall sockets. When I woke up later on, I noticed that downstream sync rates were really low on lines 2, 3 and 4. I performed a SNR reset on these lines using clueless.aa.net.uk and forced a resynch on each of the modems. The downstream speeds were still disappointingly low again.
And guess what, the culprit is evidently the hollow downstream SNR vs frequency phenomenon on lines 2, 3, 4. So I’ll have to contact AA.
Live sync rates, all at 3dB d/s 6dB u/s SNRM:
#1: down 2876 kbps, up 529 kbps
#2: down 2560 kbps, up 522 kbps
#3: down 2080 kbps, up 386 kbps
#4: down 2026 kbps, up 627 kbps
Notice the exceptionally high upstream speed of line #4 - weird.