At the end of January my local exchange got the 21CN upgrade and my line was changed to ADSL2+ shortly after. Prior to this I had sustained a full 8mbps ADSLMax connection with the following stats:
Down Sync=8128Kb/s LoopLoss=12.5dB SNR=14dB
Up Sync=832Kb/s LoopLoss=4.5dB SNR=16dB
For the first 8 days everything seemed great on ADSL2+, the stats were as follows:
Down Sync=20088Kb/s LoopLoss=17.1dB SNR=5.1dB
Up Sync=1240Kb/s LoopLoss=2.3dB SNR=6dB
There were a couple of resyncs, but the line was training so it was expected, however on the 9th day things became really unstable. Between 1am and 9pm the line resynced 47 times. Since then the line has had a couple of days where everything seemed fine and then periods of massive instability for no reason.
I've been using a DrayTek Vigor 120 plugged into a Linux server which does the PPP and NAT / etc, that modem has been rock solid since the day I got it. I've also tested with 2 separate Netgear DG834GT's both in modem (PPPoE bridge) and standard router mode. The line was refitted a few years back because the old line ran along the front of the house and the covering had been destroyed by the weather (we think it was the original line for the house). The new line is less than 50cm from where it emerged from the ground to my phone point.
There is no extension wiring, at all, and I'm using an ADSLNation filtered faceplate which I bought two years ago because the plug-in filter was sometimes causing net drops when the phone was used.
I'm really stumped as to what could be causing this. AAISP have been great and suggested trying a 9dB SNR but that hasn't helped. I've run routerstats and caught the line dropping on a graph, if that's any help:
Also, here's the line monitor graphs from A&A, I've left the stable days off, just showing the huge disconnects due to resyncs:
Has anyone seen anything like this? It's becoming infuriating and any help you could provide would be great.