PPP and LCP errors

I've been having a lot of issues with my broadband where it syncs up ADSL layer fine, but then goes into a cycle trying to connect ppp, sometimes for 20 hours, until it does eventually authenticate and give me an ip. Once it completes ppp successfully, the connection usually stays up for a few days

What would cause this to happen? If ADSL sync is good and stable then it can't be a line fault, can it?

I even noticed that with an SNR margin of 45db it was doing the same thing, connected ADSL at 256kb downstream but then could not complete ppp for several hours. Until this problem started to happen it was quite happy on a 6db margin, I'm not that far from the exchange.

Talk Talk are useless, they want to send an engineer to my house, even though I am connected direct to the test socket, no phone connected and have tried 2 different routers, microfilters, cables, etc, all with the same result!

Any ideas?

The engineer if free is usually way to go as they get independent check that not you,

45dB noise margin sounds very wrong. What are full line stats when its working?

In reply to a post by Sheepster:

I even noticed that with an SNR margin of 45db

Surely that's your Attenuation?