Are these uncorrected errors excessive?

[#1]

At least that proves you shouldn't need to double filter the DECT. Check the wires on the back of that  "plug-in" socket 

[#2]

mmm ok well that dropped my connection   all five pin outs in use on the plugin.cannot open plug in as it seems to be "sealed".
On the socket it goes into only 2 and 5 wired (blue/blue stripe).
Ring wire has been removed from all extension points.
Do I now put the router direct into the master and remove the plusgin/extension wiring extension and note the values as I'm getting 1.5-2.0 SNR now ?

[#3]

RX Blocks 19491 Errors 12010!!!

[#4]

What were the colour of the wires on the five? pin-outs (would have thought it would have been 4 or 6 pinouts). Um, what "all extension points"? No surprise you can't get into the plug-in bit itself. This master socket - does the back of it look like an LJU master as shown about 1/4 way down.
OK, be careful. How many losses of sync have you had all together in the last hour or so? If only a couple should be OK. BUT I suggest from now, the safest way is the login to the modem/router, drop the PPPoA session first, then power it down and pausing before unplugging it or the filter from the line. Pause for at least 10 minutes before powering up after reconnecting everything. Don't do this more than about 5 times in an hour. You will probably need to login to the modem/router again and click Connect for the PPPoA session.
With that level of errors I wouldn't do any more messing around after this next swap as the DLM may take exception and raise the Target SNRM or band you. So if it's convenient  to leave the modem/router plugged in at the master (for the time being anyway) -
I'd connect like this - filter into Master - modem/router into filter  .Plug-in extension into filter (so you can plug a phone in at the extension if you want), and if you want, plug a phone into the plug-in, if that all makes sense.
When all done post the stats just after connection.

[#5]

Extensions (2) from the extension cabling.
Like LJU- yes.
Colours - will need to unplug again to do that subject to process you describe - will do that next. We've had one reset so far tonight.
Uncorrected errors now 13867 v blcks rxd 695175
Process to disconnect/connect all noted.
Did you want the router on the master socket as part of this next disconnect  as it isn't at present....?

[#6]

Yes, end up with the filter straight into the master and modem/router straight into filter.
So if I've got this right then - plug-in extension lead goes to a socket, that socket has more extensions wired to it - are they plug-in as well or hard wired. Check the wire colours at all, whilst you are powered down and disconnected.
Edit: errors have only had a small increase since last report, so it may have been a burst of errors, maybe whilst you were looking at wires etc.

[#7]

Ok...the colours ... 6 this time  
Green stripe?
White
Orange stripe
orange
blue
Green stripe (again!?)
Looks very promising.
Just the small problem of the router not being where needed and loss of 4 hardwired connections (RJ45 LAN)
But errors and line performance look very good - never saw this difference with ADSL1 ever.
So if this suggests the extension wire is the culprit (even with ring wire removed), I need to find another way to reach the same end point using something that doesn't suffer from the same problems?
PS. think I'm banded though. Download speed only 6.5Mbps or is that a wireless limitation I'm now seeing???
G.

[#8]

That could be a wireless limitation, it's the sync speed that gets banded and you aren't, it's much better. (It will take time for Plusnet's profile to catch up with the new BT one).
The colours of the wires, if those are throughout all the extension sockets sound promising. You haven't mentioned if the 2nd and 3rd sockets are hard wired or plug in. What is important is the bell wire is not connect at the plug-in end (as well as the socket end), so you need to get into that plug-in bit and snip the Orange+white trace and ideally it's mate White+orange trace - alternatively you could gently get through the outer sheath of the cable as close to the plug-in bit as possible and snip them there. Essentially you only need Blue+white trace and White+blue trace connected to terminals 2 & 5 and plugs throughout. I wouldn't worry about the green ones because they won't actually be connected to anything at the Master socket.
If you try that and if it doesn't work then you will need to buy some CW1308 cable, some 3.5mm cable clips and a Disposable IDC tool from the tools page.

[#9]

Hi Anotherone,
The extension sockets are the white box plug your phone into types. The only one that was is use was connected to the router!
Given the extension run is long (around all the skirting and doors), the as-the-crow -flies distance is short between Master socket and study, but would need to cross a long hallway!
Would an Rj11 to Rj11 low loss cable be a better option, not least as it's shorter, so long as I can run it under carpet, through a couple of stud walls etc?
I could certainly try and snip the bell wire on the plugin ext, but the plastic shell looks pretty fragile. 2 + 5 are certainly all I left on the 2 extension boxes.
The sync speed is 3Mbps more at the master to the end of the extension, so again the shorter the run the better. I do have a disposable krone tool from my last foray into bell wires and such things ...so could use that I guess.
Many thanks for all your advice - much appreciated.

[#10]

There's no point in using a RJ11 to RJ11 as you've described, running cable under carpets etc it a very bad idea as well. If you go up a page from the link I gave the Pro-cable would be the type you'd have to use, and frankly it wouldn't be as neat a job as hard wired CW1308 either.
I'd just get through the sheath of the plug-in cable close to the plug-in bit and snip the wires there. Then use a bit of white tape round the cable to tidy it if needed (or sellotape  ).

[#11]

Ok, have snipped both orange/orange trace wires inside the connector...although I have a strange feeling I have already removed the ring wires inside the master socket....
Agree what I proposed wasn't the best,  was just trying to avoid miles of cable to get to where the router needs to live..... (bungalows!!!!)
If I went the CW1308 route, what are you proposing as the means by which I terminate the ends into the master socket and at other end?
Thanks again,
Graham.

[#12]

The master socket has a yellow capacitor in it, which is what provides the "Bell feed" to terminal 3 (you can't get rid of it either because with a series resistor to the other wire, it's used for line testing!). So basically you don't want to connect to terminal 3.
IDC terminals both ends? I'll send a PM.

[#13]

Ahhh okay, I'm showing my ignorance well tonight  
Look fwd to reading your PM Anotherone.
And once again, I cannot say it too often; Many, many thanks for all your help.
Graham.

[#14]

Darn!  It was all looking so good until 10 minutes again with SNr fluctuating once again to 2.5 a nd then everything just freezing  on both systems here...no browserconnection to the web, on either PC; XP network diagnostics eventually a sea of red unable to connect using FTP,HTTP,SHTTP and so on. The only thing that was there was a line syncing at 15001200 (now 15181100 after rebooting (drop PPPOA, switching off) router with a  10min gap) with a meagre 2.5 SNR. SNR still fluctuating 2.5 to 3 as I type...
Now what?  I'm stumped for sure...new router? do I just connect on 992.3 ADSL2 - i.e. is this 2+ just too much for the line?
Uncorrected errors were a lot less this time around but still there.

[#15]

Hmm. Fist just check that the snipped wires aren't touching - snip a touch more out if your aren't sure.
I think what I would try next is one of WWWombats suggestions. Configure your PC to use one of the other DNS sources as the Primary, with the Modem/Router as a secondary. That might help eliminate any DNS related issues.
Also go to http://www.vwlowen.co.uk/internet/files.htm and download and setup RouterStatsLite. Set the sampling at 10 secs. 720 points per page.
Can you spot any pattern to these occurrences? eg. central heating coming on (but not necessarily each time), phone being used, incoming call? Any other electrical events?
When you spot an event, promptly check your phone line for audible noise.