Disconnects every 30mins

Virgin ADSL (LLU). Netgear DGN2200. Wired connection. History of a poor noise margin on this line.

My line has long-standing intermittent issues with briefly (<1min) losing its DSL connection which I had been wondering might be to do with line noise as I have intermittently heard this on the line too. I also often get a dropped connection when the phone is answered despite both phones having new microfilters. I was going to get BT to sort the line noise and hope it fixed the rest but it's so intermittent I cancelled as I didn't want a £100 charge from them for a call-out if all was well at the time.

Last night whilst running RouterStatsLite I noticed my connection drop at 10 to the hour and 20 past the hour like clockwork. I had earlier in the day downloaded >1.5GB from MSDN.
Today my connection started off OK and I set the PC downloading perhaps 1GB from Microsoft again (I get about 300KB/s). When I got back I saw that after a few hours it had started doing the connection dropping at 10 to and 20 past again! Noise margin has been between 8 and 10 all day.

I can't think of anything in the house that would run like clockwork like this!! I am half wondering whether Virgin are throttling me in some way for downloading a gig or two in the day and the manner of the throttling is in some way to blame.

I'm only here a couple of days a week so it makes doing anything other than brief troubleshooting difficult - esp since not all the PCs in the house could use wireless if I move the router to the test socket and disconnect the phone.

Does anyone have any suggestions as to what may be going on and how you'd proceed? Especially regarding the regularity of connection loss and disconnect on phone use despite new filters.

Stats from the router:
https://dl.dropbox.com/u/12596937/RouterInfo.png

Thanks!

Do you have the connection timeout enabled in the router?

Best to disable that.

I can't spot a disconnection timeout setting. It was still disconnecting while we were using it though.

Further testing from a little earlier on:
I tried powercycling the router. After it had reconnected it dropped the connection just over a minute later and then came back. It was then happy for five minutes until at 20 minutes past when right back on its previous schedule it dropped again! I've now just done a quiet line test and my use of the phone made the DSL drop. The line is currently audibly noisy. A quiet line test in the test socket also revealed noise.
The next due disconnect at 18:50 did NOT occur (the first it's missed bar one exception since it started at 13:20pm). I've just done another quiet line test and there is still some noise - both picking up and hanging up the phone caused it to drop. The 19:20 time has also now been and gone with no d/c.
Very confusing...

I just started plotting the upstream noise margin too and spotted that earlier in the day when the downstream graph had looked happy, the upstream noise was dropping to the bottom suggesting a disconnect even though the downstream one wasn't - at ten to and twenty past!
It's been otherwise generally steady but sometimes goes crazy. Here's a recent graph of it doing that. The first disconnect is my picking up the phone to do a quiet line test. The second is from my hanging it up again.
https://dl.dropbox.com/u/12596937/Upstream.png

Picking up the phone should not cause a disconnect anyway, and if the upstream is playing around it points more to a filter issue e.g. one that is not isolating the two parts of the spectrum in a neat manner

Try with ONLY and ONLY the ADSL modem connected to the line at the test socket.

It's running less than half speed.

line noise as I have intermittently heard this on the line too

Have you tried BT Quiet Line Test (17070 Opt 2) with router discon'ed? If you get any noise report it to phone line provider as a voice fault; do not mention BB.

Have you removed ring wire?

Can't explain regular discons, but does it happen when plugged into test socket hidden behind faceplate?

OK I'll give that a go next weekend when I have some time here again. Obviously I first have to verify it's misbehaving before moving it and depriving the house of a phone for a while! Also deprives me of my XBox's connectivity!

I've changed the filters in the house in the past and also tried doubling them up and then eventually gave up and brought relatively expensive brand new ones that I'd read of as being recommended. No change though.

I hope to post back at the weekend with results of the DSL Modem on its own in the Test Socket. Thanks for your help.

I earlier tried the Quiet Line test with a phone (+filter) directly in the Test Socket and still heard noise. I have been very tempted to report it to BT (yes, not mentioning DSL to them) but have balked knowing that the issue is intermittent and that I risk them trying to charge my parents' £100 in my absence if the test is normal when they visit.

I did previously try one of those faceplates that disconnects the ring wire but it didn't help and so I took it off in case BT didn't like it.

Needless to say, having had RouterStatsLite running all day today, it's been stable with only one brief loss of connection. Upstream noise margin has been rock steady and downstream noise margin has not varied a great deal.
Will see what happens tomorrow.

Pretty uneventful today too.

Started the day with a downstream noise margin of 13 and an upstream one of 6. Had one disconnect late morning and reconnected with a downstream margin of 9. That gradually went down over the day and when it got down to 3.5 just now I sensed an imminent disconnect. My Skype died briefly but no disconnect was seen on the graph. Skype came back and died again so I rebooted the router.
Noise margin now 8.5 to 9 again. Upstream noise margin rock solid all day like yesterday.

Will be interesting to see if chaotic connections return when we get lots of wet weather again. Will test again next weekend. Next time it starts being unstable I'll be moving the router to the test socket.

Any ideas why the noise margin should gradually deteriorate during the day?