After all the snow, my BB sync speed dropped:

Up Speed 576000
Down Speed 2720000
SNR Margin 6.0
Loop Att.18.5

And of course my profile dropped soon after to 2000. Up until this point my sync had always been 8128000 and my profile 7150, and was impressively fast.

After a week of messing (and being told it must be my router at fault) a got into the habit of switching off the router each day and switching it back on. After 3 days of this my sync recovered:

Up Speed 832000
Down Speed 7616000
SNR Margin 13.0
Loop Att. 19.0

So I assumed all was well with my router and as usual BT had messed something up at the exchange. My profile soon improved to 6500.

So today I'd thought I'd switch the router off and on again to see if I could reclaim the last ounces of speed back. Naturally this didn't work and my sync speed has now plummeted again with my profile following down to 3000 soon after.

Up Speed 832000
Down Speed 3552000
SNR Margin 8.5
Loop Att. 19.0

Can anyone please provide any insight? Is my router dying (it's a Vigor so not totally cheap rubbish)? Or is this most likely a BT / line / whatever issue.

My ISP were pretty useless at trying to resolve this. As far as I can tell it got better by itself or else BT fixed something then (as usual) denied there was anything wrong.

TIA.