adsl2+ sync, BT profile, and disconnections

After having a solid adslmax connection, I was upgraded to "upto20mbps". I was told that there would be disconnections etc for about ten days.

However, I'm now getting disconnections which reconnect immediately maybe about once a day. This is on a fully filtered Netgear DGN2200 upgraded to the latest firmware with an iPlate which has also started syncing higher for over a week, at 15143 down, and 1256 up, while my BT profile is 11000

http://i177.photobucket.com/albums/w235/2pods/Router...

Any ideas ?

Your margin is very low (2.8dB) that would be why.

If you can graph the router (MRTG, Routerstats etc) then watch it when you get a disconnection and see what it reports. It's also worth checking all your internal wireing etc etc.

You will end up on a 9dB profile which should stop you dropping the line, however it will start to eat into your sync speed.

Either leave it to it's own devices and down to the BT DLM system, or call Zen and ask for a 9dB (Or higher) target margin. (Though this *WILL* impact your sync)

I've phoned Zen, and am in the process of doing the usual stuff (router plugged into the test socket, trying to scounge another router), and will change the filter tonight.

When you say it will affect my sync, does that mean what I'm actually synced at (if so, I won't miss much, as I'm synced at 15000 something, while my speed and profile is about 10600) ?

"Each 3dB increase of SNR is worth anywhere between 400 to 1200kbps of Sync speed drop."

Your Profile is so low because you have been disconnecting.

How did you end up with such a low, 2.8 dB, NM?

I've no idea.

This was just before 21N upgrade
http://i177.photobucket.com/albums/w235/2pods/Router...

This was just after the upto20mbps upgrade
http://i177.photobucket.com/albums/w235/2pods/Router...

and you've seen the current one.

I meant to ask. What is NM ?

On 21CN the BT systems can adjust your target Noise Margin down to 3db under certain circumstances (I was told if BT systems see the line as ultra stable at 6 it will reduce it). If your noise margin is 3db after a re-synch I would ask Zen to increase it to 6 if you want more stability.

I manage a line with these stats which is ultra stable and has an SNR of 3 for months
Mode State Up Speed Down Speed SNR Margin Loop Att.
ADSL2+(G.992.5) SHOWTIME 1239000 22073000 3 8

NM = Noise Margin.

I think you've got to a low NM = 2.8 dB cuz 10 days ago you re-synced with a standard NM of 6 dB and since then noise on line has increased so that its margin has been cut.

After changing a filter last night, there was a bit of an improvement (though later on it was showing a margin of 1.8 !).

No doubt I'll jinx it, but according to the log, so far there have been no disconnects since about 11.00pm last night and the current NM is 4.5db.

The longer cable etc should come tomorrow, so I'll try it in the test socket then.

Longer cable still not arrived, but it seems to have been stable (touches fibreboard) since the filter change.

I have a steady downstream sync of 14834 kbps, upstream 1252 kbps, NM 4.1 db on a 28.5 db line.

Assuming it stays like this, will the IP profile rise or stay at 11000Kbps ?