Been having terrible trouble with my ADSL line. Over the last couple of days its kept dropping, getting disconnects sometimes after a few minutes or sometimes after an hour. Numerous phone calls to BT, they said my line was OK and it must be the microfilters. Tried 4 filters, no change. BT said it must be the router and will send me a new one but not until next week!
So being the impatient type I bought a new Netgear DG834G - actually not that expensive - but the line still dropped. So, back on to BT, spoke to Tech Support in India and they promised to test the line and ring me back after about 30 minutes. Well that was 9 hours ago and no-one has rung back yet! Having said that (and I'm tempting fate here) the line has been up ever since, so maybe they did something.
I've been looking at several support sites and I've come to the conclusion that the problem is to do with the Signal to Noise Ratio, apparently if the SNR margin is too low the modem won't keep the DSL connection. At the moment my downstream SNR Margin is 27db - it's a pity I didn't know what it was when the line was dropping but when the line is down you can't tell.
So I'm monitoring the connection. Apart from chasing BT, I also have some tricks to try, for instance to boost the SNR I can "rewire" my phone socket to disconnect the ringer wire. I'll post any news here. Meanwhile, if you are interested visit
www.adslguide.org it's a good starting point.