I've been having an intermittent problem with slow internet connection speeds over the last month and a half.

Initially after a week of random slow speeds (sometimes the connection was normal and sometimes slow with no pattern to it) I did the bt speedtest which showed a speed of about 400kbps on a line that should have been getting between 2000-4180kbps. My ISP sent me a list of questions for troubleshooting (which I completed), but speeds suddenly became consistently good again and remained so for 10 days before I started having random slow speeds again.

My ISP have said they can find no fault with the connection and would raise it as a fault with BT if I agree to possible engineering charges of £183 if no fault is found. As it is an intermittent problem I am concerned they won't be able to find a fault so am not taking things further with them at this point.

I would like to pursue further troubleshooting myself to see if there is anything at our end of things which is causing the problem.

We do not have a modern BT master socket so I am unable to test the router bypassing our internal wiring.

The connection problems are evident on 2 different computers.

I am currently using a Netgear DG834G with the most up to date firmware and have checked all settings given by the ISP. I am waiting for a replacement Netgear router to test the connection with different equipment. I briefly tried a speedtouch modem which worked for 10 minutes before it disconnected and lost the connection altogether.

One thing I noticed during my investigations so far is that the Noise Margin becomes really low when the speed drops (down between 2db-0db) attenuation remains constant at 39db. When the speed is OK the Noise Margin seems to be around 6db-9db.

Does this show a problem at our end of things and is there anything else I can try?