Still dropping connections after 3 months and 3 Openreach visits!

[#1]

I'm beginning to feel like I'm going to have to give up on my long pursuit of better speed. For the full tale ticket 29265416 is available for James and friends to read over, but the short version:
After steady connections for 3 years, speeds dropped to 250K, leading to fault initiation. Usual steps undertaken (several times now)-test socket, different modems, faceplate, ring wire etc. Speed got up to 1.1M but would then unpredictably crash down again, taking the usual 3 days to recover (even in test socket). PN see dropped connections and resyncs, so Openreach appointments made.
3 visits, each unique in their own way. 1st guy tested the line at the exchange and master socket, got 3.6M sync rate and did little else (I can get this on modem startup, but it drops after a variable, but fairly short time). 2nd visit, thorough line checks, no errors, synching at 2.9M. This one rewired master socket to the upstairs study and made the hall one an extension, fitted BT split faceplate and left with my modem synching at 3.1M. Within 30 mins, it had dropped to 500K. Improved to 1.1M during the week but PN still seeing drops, so visit number 3. This one removed the faceplates, made the downstairs socket the master again, and refitted my ADSL filters to each extension. Also got the line gain turned up, even though the quiet line tests were silent. He left with my modem synching at 2.3M, which lasted about an hour-back to 1.5M last night, but PN profile set at 750K.
My line? Underground cable. Reports 3.8km to the exchange even though KItz.co.uk makes it 2.7 by road and 1.7 direct. Downstream attenuation of 52-56dB, SNR anything from 4 to 19 dB, usually between 12 and 15 dB. Should be capable of 2-3M at least?
Have I run out of options? I'm on the verge of going with mobile broadband!

[#2]

Hi Steve,
Sorry to hear you haven't had much luck getting BT Engineers to sort out your problem
In your last ticket reply you stated "Engineer visit complete-he reversed most of the changes made last week. Had the line gain turned up as well. Will shortly reconnect to the master socket and see what results."  What was the stability like in your test socket before you moved back to the master socket?  Or when you were saying that did you already mean that you were connecting to the test socket?

[#3]

Have you tried a different modem?  Maybe it works normally initially but then drops in performance as it warms up?  By the account you give, you always get a good result whilst the BT Openreach engineer is there but it goes wrong later.  Ideally your SNR should be 6dB.  Anything greater means your exchange equipment has concluded your line is poor and cannot cope with 6 dB.  A faulty modem could cause this, I imagine. 

[#4]

Hi james, thanks for the speedy reply. I'm now connected via filter to the newly rewired master socket, but not in the test socket at the moment (I'm at work so can't change it until later).  Sky box is not connected. Router (ZyXEL) is on 24/7-is the line currently stable? (I was fiddling with connections etc during the afternoon yesterday so drops then my have been me switching things around from upstairs to down. My best speed while in the test socket was 1.2Mbps, whic held for 4-5 days a while back.
To Reed Richards-have used 3 different routers, my original PN Voyager 2100, a new Linksys 160N (most unstable with this one), and the ZyXEL 660HW-D1 which gave the most stable ongoing connection, and picks up the line itself when it drops, rather than me having to reconnect.

[#5]

Thanks Steve,
I'd be interested to see, if possible, if you could stay plugged into the test socket throughout the course of the weekend and see if the speed and stability of your connection remain.
If not (especially if there are connection drops) then we'll need to get BT out again

[#6]

Ok James, I'll leave it in the test socket all over the weekend, in fact from about 6pm tonight....
I suppose you're familiar with the fact that BT don't seem to keep a record of previous issues, as I've had to explain the whole problem to them every time.....

[#7]

Quote from: SteveE

To Reed Richards-have used 3 different routers, my original PN Voyager 2100, a new Linksys 160N (most unstable with this one), and the ZyXEL 660HW-D1 which gave the most stable ongoing connection, and picks up the line itself when it drops, rather than me having to reconnect.

All routers should re-establish the connection automatically if it drops, although you can often turn off this feature.  Re-establishing the connection is almost always the default option (although I remember an old Belkin router it was not). 

[#8]

Router in test socket, all phones disconnected. Will remain on 24/7 throughout the weekend. I've updated my ticket, asking for checks for dropped connections over this period.

[#9]

Ticket response on Saturday said it apears your problem is resolved, please rebooot your router to see new speeds. If new speed means the same as ever before (1.1 Mbps) then yes, that's what I had during yesterday, but this morning it's back to 750k. I reconnected the ADSL faceplate last night, and the home phone into the Phone socket of that plate. Surely with the separate sockets, I should have maintained the same connection?
My SNR is also still all over the place, varying from 1 dB to a more common 15 db, with other values in between. I had asked for data on how many dropped connections I was having over the weekend-does the reply I got suggest they weren't seeing any when I was in the master socket?
Still no further forward really....

[#10]

You were plugged in to the test socket, the ADSL faceplate plugs in to the test socket, so you must have unplugged the router and then plugged it in to the faceplate. So why do you think you should have maintained the same connection?

[#11]

Just wondering... Are your connection drops a continuous problem or an intermittent one? I'm getting drops every few weeks that affect my speed for a few days and then appear to go away. Just wondering if your problem is similar. My problems only started a few months ago.

[#12]

To jelv: Sorry, maybe I wasn't clear. I meant the same connection speed, obviously I had to reboot and reconnect. My question was why the speed dropped to 750 from 1100.
To jayed: My experience seems very similar to yours-I'd never noticed problems until May, and since then it's been up and down regularly. When stable, it holds 1100 or so, then drops without warning to 250 or even less. 3 days later, usually back to 1100. It's the unpredictable part that's most annoying.
I've been with PN for more than 7 years, but not enjoying the current experience (although support have been helpful and persistent).

[#13]

BT set a target noise margin. If you look at your noise margin immediately after rebooting the router that is your current target. It starts at 6db; if BT think your line is unstable they increase to target in 3db steps until they find a setting at which it is stable.
The way the target is used is that each time you sync the exchange and your router negotiate to find the fastest speed they can connect at while staying at or above the target noise margin. The noise margin will vary during the day, during the evening particularly it will go down due to increased interference. Your changing things around last night probably meant you reconnected at the worst time.

[#14]

Now at 2048K with a SNR of 13dB on initial resync, but after last night's blips, BT have set the line at 500K, so another 3 day wait.....

[#15]

After a few days at 1100, today I'm dropping steadily...900...700...450...back to 700. What's going on? IP profile is set at 750k, SNR gone from 15 to 10 dB.
Router etc still plugged in via ADSL split faceplate, no other changes to phones etc.
I'm losing the plot.....