In reply to a post by grumpysod:

It's held a connection for up to six days.

Heres the output just after a reboot

Line Mode ADSL2+ Line State Show Time
Latency Type Fast Line Up Time 00:00:01:22
Line Coding Trellis On Line Up Count 2
Line Power State L0

Statistics Downstream Upstream
Line Rate 3071 Kbps 443 Kbps
Noise Margin 26.4 dB 26.0 dB
Line Attenuation 38.5 dB 18.7 dB
Output Power 0.0 dBm 12.2 dBm

It looks like you are on a banded profile, at the top end of the 1472-3072 band. I think the maximum target Noise Margin is 18dB, so the value after reboot being much higher than that supports the banding assumption.

Leaving the connection alone so the DLM sees the line is stable seems the best way forward with this. Patience is needed since it can take 2 or more weeks for the DLM to react. When it does your connection should re-sync automatically.

Had you seen Dave Tomlinson's post on the Community forums - might be of interest to you.

In reference to community.plus.net/forum/index.php/topic,82081.0.html:

Hi all,

BT are about to start a DLM test that will allow ISPs to set specific line profiles on individual customers' lines including setting a hard over-ride on the line so that DLM can't change it.

The trial is set to begin in early January so we're looking to get together a list of up to 100 volunteers whose lines we can test out. We'll be using some staff and a couple of our test lines but the more volunteers we can get the better. So if you're interested in taking part (Asbo your name will be already on the list ) please add a reply here.

It would also be useful to post what line profile you want us to set. We don't have the final list yet but it's likely we'll get a choice of the following options:

Interleave - off/on
Target SNR - 6/9/12/15dB (possibly 3dB as well) on both upstream and downstream
Standard set of banded profiles

If the choices are different we'll let you know.

Any questions please ask.