Ongoing disconnections and solutions almost exhausted

[#1]

We've had a fault open for two and a half months now and seem no closer to a solution. Having read a few threads on here I wonder if some of you clever people might be able to suggest what's happening?
I raised a fault at the beginning of September as our connection was constantly dropping and the router resetting. Since then we have tried a total of three different routers, had interleaving switched on, had BT in twice to change the master socket, upgrade it to a REIN-proof socket, change the cables on the outside of the building, perform a 'lift and shift' to change the cables from the exchange and had  a cease and reprovide. REIN in the property has been ruled out. There are no new appliances and no extension sockets. There is no noise on the landline.
The problem persists - and has even got worse -  with plusnet unable to explain it and BT now claiming it's definitely not on their side. The disconnections are now particularly bad from around 4pm to 10pm, but also happen through the day. When the fault was first reported We're unable to use our VOIP phone for work calls and struggle to stream any video content, particularly in the evening.
The router we're using currently is a Netgear DGN 1000, but the problem is the same with a Linksys WAG160N and a Thomson TG582N supplied by plusnet. When we use the other two routers they need re-booting more often after a connection drop, where the Netgear more often resets itself.
We have considered moving to another supplier, but were persuaded by plusnet to stay, and now feel nervous about moving in case the problem comes with us.
Any suggestions or is there any further information I should supply that could help to shed any light on this? Thanks in advance.

[#2]

Welcome to the forums.
If the issues are with the line then moving provider won't help, as they will be using the same BT phone lines (unless there is a cable provider like Virgin available).
The fact you have tried more than one router should rule that out as being the problem.
To help the others who will now doubt be along later with some better advice than I could give can you post up the details as discussed in this thread - http://community.plus.net/forum/index.php/topic,96155.0.html

[#3]

You seem to have tried everything I can think of except Routerstats.  This is a program you run on your computer that monitors the line rate and noise margin on your router by polling it every 15 seconds (by default).  That might give you some insight as to what might be causing your disconnections, for example whether these happen out of the blue or against a background of increased (high frequency) noise on the line.  You may need to use the 'Lite' version of Routerstats to work with your router; I'm not sure.  http://vwlowen.co.uk/internet/files.htm

[#4]

Thanks for your replies. We have set up routerstats and will add the other info tomorrow.

[#5]

We've had routerstats running for 24 hours. Can someone tell me specifically what data would be useful from this monitoring?
Plusnet speed test results -
Estimated - 6mb
Current - 8.5mb
bt speed test results
Download speed - 8.18
Upload speed - 0.36
Ping latency - 86.13 (did several tests and this varied between 45-90
Router stats
      Port      Status     TxPkts       RxPkts      Collisions  Tx B/s      Rx B/s       Up Time          
      WAN       PPPoA       53014       84409       0           4854        54140       00:29:55          
      LAN       10M/100M    71633       41761       0           46672       3719        00:30:57          
     WLAN       11M/54M     17898       14335       0           7084        1381        00:31:01          
       
     ADSL Link             Downstream     Upstream      
     Connection Speed      11926 Kbps      440 Kbps    
     Line Attenuation      33.0 dB         19.4 dB    
     Noise Margin          8.5 dB          27.9 dB
I've attached the most recent snapshot from plusnet - interestingly, when the problem started the disconnections were random throughout the day. Now, as you can see, they do occur during the day (and night), but are concentrated during early evening. I'm told that if it was because the network was overloaded we would get slow speeds rather than disconnections...
Apparently BT are going to come out in the afternoon at some point so they can witness the disconnections, but I'd still be grateful for any suggestions.

[#6]

The most interesting data from Routerstats is how the downstream noise margin varies with time.  In your stats it is 8.5dB, which should give you a fair bit of headroom, but this is obviously not enough to prevent disconnections.
You seem very prone to disconnections between about 16:00 and 20:00 so it looks like you could be suffering from electrical interference from some device that is typically on during this time and typically off otherwise.  This could include your computer!  So you might look at the Routerstats graph and see a drop in noise margin beginning late afternoon and recovering mid-evening.  But, obviously, you won't see that if you are running Routerstats on the computer that is causing the problem.

[#7]

I've attached a graph from Friday and from early afternoon today.
It may be coincidental, but I'm having great difficulty getting plus.net site to load - today's drops so far coincided with me trying to get onto my account to see if there was any update. When I finally logged on via 3g on my phone I saw that my last reply on Friday hadn't posted, which is why we haven't yet had an appointment for an engineer.
We're online all day and evening pretty much every day, and running router stats on a separate computer. We've ruled out interference from anything in our flat, by having everything switched off (including the fridge/freezer, whoops) and still having drops. I wonder if it could be connected with someone's heating being between 4 and 8pm, but that doesn't explain the random drops during the day and that wasn't the pattern when the fault first started in September.
I'd still be grateful for any more suggestions

[#8]

Hi lucyp,
I've spoken with Daryl and he's continuing to pursue this to get it resolved for you as a priority.

[#9]

Thanks Chris, I just thought it was worth posting on here as well, to get the benefit of lots of people's expertise and experience.
We have an engineer booked for tomorrow afternoon.

[#10]

Glad to hear it, hope the visit gets things sorted for you - please let us know how it goes.