>> doesn't that mean that my IP address wasn't my normal one, as I was logged in to a different server?Yep.. its a BT domain one irrc assigned by the BT RAS - and why I didnt bother removing it when I took your phone no out.
>> The ISP cant reset the BRAS profile - unless its a stuck bRAS.Understood what you meant.. The ISP cant ask BT to reset the bRAS profile unless its stuck - the bRAS profile is dynamic and can change (as you are finding out) every time you sync at a different speed.
By the time it will have been processed.. it will have probably been changed by the DLM anyhow.
It takes the DLM 3 days for upwards and 75mins to go downwards.
>> but I get good SNR even at these low levels.But how good is good?
The higher the speed you sync at the less your SNR is.
Each time you resync with MAX, the product is designed to run with a target SNR and a margin.
Depending on the target SNR set on your line (default is 6dB), then the DLM will always try and give you the highest sync speed it can whilst maintaining a margin.
Its a bit hard to explain.. but take for eg my own line
I also have a 7dB attenuation line which is close to the exchange.
Im currently syncing at 8128kbps with an SNR Margin of 14dB.
When I synced at 2272kbps my SNR Margin was 31dB
When I synced at 1152kbps my SNR Margin was 35dB
iirc when sync at 512kbps my SNR Margin was 39dB
My target Margin is (default) 6dB.. which means that on this line I have an additional 8dB to "play with" so if I wasnt restricted by 8128 being the max speed then the line would be able to handle even higher speeds.
However, for some reason your line is being problematic.. the DLM will have therefore increased your Target SNR to either 9, 12 or 15 dB.
At a guess your Target SNR is 12dB.. therefore every time you resync.. your router will negotiate the highest line speed it can whilst still having an SNR Margin in the region of 12dB.
This happens each time you (re)connect.
The SNR Margin will then be subject to variations once you are connected because thats what it is supposed to be - a safety margin. Once that margin drops too low then you loose connection.
Hope this makes sense.
Have a read of An explanation of SNR and SNR Margin
http://www.kitz.co.uk/adsl/linestats.htmRoseway has also written some very good info here
http://forum.kitz.co.uk/index.php?topic=147.0