Noise Margin

[#1]

Noise levels increase after dark and that nasty flat extension cable you are using is probably picking up lots of noise. How much that may be contributing to your problems is difficult to say. Once you have that twisted pair cat5e that will eliminate one issue.
You are going to need to "modify" the window-sill though. It was suggested you try posting a photo of it, in case there were any bright ideas someone could suggest!

[#2]

I agree about the master socket as the error rates are extremely low over nearly 3 days and it is unlikely that a reduced noise margin would have the effect you suggest

[#3]

Attached photo of my BT master socket.  The two disconnected cables you see are from my Sky boxes
@ Jim - I was clutching at straws about the noise being an issue, since I don't have a clue why I get the spikes I do and noise was suggested to me as a possible cause by a third party.  I freely admit to having no knowledge about it and am relying on the expert help on here.
I get that things can be a little variable but am at a loss to understand why I go from 6.5MB down to 2 or 3MB for no apparent reason.  Even more puzzling is the fact that my upload speed all but disappears at times and my ping goes from a steady 30-ish ms to well into the hundreds.
I have to say, though, that it's possible I'm being a little greedy as things have most definitely improved since last week.  Although not great I can live with the gaming lag (although very frustrating!) but the Skype situation is more than a little annoying.  Aside from the connection, I have a new Intel Core i5 PC with Win7 and 8GB Ram and Logitech cam, so can't think it's down to that hardware.  I should have enough to be able to hold a decent video call without losing audio

[#4]

That is awful but there are a number of options
That plastic strip is usually fastened on with superglue to may just be removable once you remove the sealant
However there is an easier way
You need to remove the sealant on top and bottom of the BT box anyway as it should never have been there in the first place
Cut about 10mm off the lower strip in front of the box using a Stanley Knife (it is just PVC so should be fairly easy)
Then fill the hole underneath (assuming that there is one to make it look tidy)

[#5]

I'd tend to agree with Jim's approach, clean away the sealant and try and remove the whole of the strip first. It may not even be superglued, just held with sealant or "no-nails" type fixative.
However I would trim off nearer 19mm (3/4") to ensure the front plate can fully clear the backplate. You'd be able to trim it more  neatly if it was removed. Clean up the surface underneath, (fill the exposed area if needed to the level of the old sill) perhaps apply some white paint to that area.
Refit the trim with a nice white silicone sealant, not putting any around the BT box.
Probably worth mentioning here that when you remove the front plate, this should isolate all your internal wiring, so your two extension sockets should be dead. You will need to plug your phone in at the filter plugged into the test socket.
If there's a problem with lead lengths need of a power socket etc., when your Cat5e lead arrives for your modem/router you can use the flat one on the phone side of the filter if needed, but only on the phone side!
Looking at the picture there's a fixed cable going into the back of the BT box from the right. Can you explain where this cable goes and what it's connected to? Also there seems to be a plug-in cable that's had it's bell wires cut - can you explain where that one goes?
The other plug-in one, towards the front of the picture - would that be a sky-box?

[#6]

Good tip on connecting the phone after removing the front plate, thanks!
I'm not home now but from memory the cable exiting from the back of the master socket goes to the downstairs extension socket. The cable with the cut wires belongs to one Sky box. It was there when I moved in and everything worked so I'm assuming those particular wires aren't needed for Sky's purposes?! The other cable is another Sky box. The only extension currently in use is upstairs ( phone) and the Sky cables are disconnected

[#7]

so, I've butchered the window sill, cutting away about 20mm, and freed the BT Master socket.  MY twisted pair cable has arrived today so I've plugged the router into the test socket (via a filter, of course) and plugged my phone in too for good measure, using the extension cable I had previously working for the router as per Anotherone's tip.
Immediately, I've managed a Skype conversation without having to drop video, which is a result in itself :).  Of course I don't yet know whether that's down to the cable or plugging into the test socket but it's a good start.  Many thanks to Oldjim and Anotherone for your suggestions.  So far so good.  How long would you recommend I leave it in the test socket?
My previous connection had held for more than 161 hours without dropping, which shows that my new/old router is doing it's job in that regard much better than the old one!
On another point, the attached TBB graph shows massive spikes which coincide with my Skype conversation, settling down when I was doing light surfing and gaming.  Out of curiosity, is it normal for Skype to produce such big swings and, if so, why?
Thanks again for your help so far
edit: forgot to add, my noise margin has also increased from around 10.3dB (at one point this morning before the changeover it dropped to 9.9) to 12.4.  Any ideas why that would be?

[#8]

Given that your sync speed is the maximum for an interleaved connection an increase in noise margin is a good thing as it shows that there is a lot less noise on the line
Now that you have managed to removed the lower front plate how many wires are connected to it

[#9]

Not sure if the attached photo is that clear but i can see one white, one green and a pair each of blue and red

[#10]

anotherone may have a better idea but, other than looking a total mess and a botch job, it appears that your wiring is in the star configuration (all wrong) and that the bell wire is connected to terminal 3
I think you said earlier that you only use one other phone socket in the house. If this is the case you could disconnect the other one from the faceplate (you can tell which one it because the ring wires are two different colours) and disconnect the ring wire as well leaving only terminals 2 and 5 connected
However let us see what anotherone thinks before doing anything.
In answer to your earlier question - as your internal wiring is such a pigs breakfast leave the connection to the test socket until we decide what to do about the wiring
One further thing you could check - if you look at the other sockets are the same colour wires connected to terminals 2, 3 and 5 as on the faceplate

[#11]

I'll have a look at the others.  many thanks!

[#12]

Oh dear, as Jim says, a bit of a pig's breakfast. Apart from the Bell wire issue, it looks as though there are two different cables there, one with the correct standard of cable with the following connected (Blue+white trace, White+blue trace, Orange+white trace - this last one is the bell wire) and the other cable, the old standard with a Blue, Orange and Green connected.
From the previous picture I'd guess that the old standard cable may be the heavily painted one that exited the rear of the box to the right, but where does the other go/leave the box - behind the vertical trim perhaps? Will await your information about the colour of the wires connected to each of your sockets.
There is a couple of potential solutions to this (it's not a disastrous situation), it will depend on what wire goes where,and where you want various equipment.

[#13]

Buy a proper filtered NTE5 from a well known auction site!

[#14]

Quote from: Oldjim

I think you said earlier that you only use one other phone socket in the house. If this is the case you could disconnect the other one from the faceplate (you can tell which one it because the ring wires are two different colours) and disconnect the ring wire as well leaving only terminals 2 and 5 connected

ah, I may not have explained myself too clearly, sorry.  I have two extensions - one is upstairs and is where my main phone is normally permanently connected (it's a DECT phone so the others are scattered around the house).  The downstairs extension is normally what the router is connected to but I have bypassed it this last week by connecting directly to the Master socket.  I would prefer to keep it connected as it's much tidier cable-wise.  At the moment nothing is connected to it

[#15]

Quote from: AndyH

Buy a proper filtered NTE5 from a well known auction site!

That solution will not work if the OP wishes to have the modem/router located at the socket which has the incorrect standard wiring 

Quote from: shure

.........and one downstairs which the router was originally connected to but which is now temporarily unused.

It's temporarily unused because he's plugged into the Test socket.