With the bell wire removed and extension removed there is not likely to be much difference in having a new master socket

Agreed re the master socket.

What is very noticeable is the huge improvement in the attenuation, noise margin and max attainable downstream sync. But whether there will be an improvement in the stability I have my doubts.

It's odd that the pristine junction box with the crimps is the first after entry to the building. Unless that is to deal with a cut cable from outside perhaps when double glazed windows were installed. I wonder if the outside part of that cable can be seen to go to a drop wire from a pole? Or if it runs outside then re-enters to the missing extension.

The decrepit one it leads to looks more likely, with what looks like underground feed and output cables. It's a very strange place to have such an old junction box if it isn't to do with the outside connection. I suspect there may be damp there, which could be the problem whatever the reason for the box existing.

Alternatively, I wonder if it is still functional. If it is even in the circuit.

Looking back at the pristine junction box, orange > orange and blue > white. With orange and white heading out together to the right. What?

Also, where do the valid pairings at the master come from. The don't seem to be present in any other pics so far, though maybe, looking again, we have the black/white + white/black pair at the decrepit box. Maybe going to the master.

There's something strange about your apparently shiny box with crimps which then leads into the second obviously older box. If it's any help, we had one of these old boxes in the roofspace and it was at least 45 years old. Could be someone had an illegal fiddle with the incoming, perhaps during house improvements?

Edited by Malwaremike (Sat 24-Nov-18 14:20:44)

Thanks Malwaremike.
Yes it is fairly new. Seemingly it happened when they got new windows put in. The dropwire from outside cable comes through the window frame into this connection box. I didn't ask who it was that did that box, but I suspect it was NOT BT/Openreach.
It's a good point.
I'm not sure what's the best way forward with that. I'm reticent about recommending having someone come in to replace it, because if it doesn't make any noticeable performance improvement, my credibility goes down.

You seem not to have read this post, where I wonder about possible damp at the old junction box. But also wonder if it is still in the circuit.

Suggest you try tracing the line all the way back. A friend's house had reasonably tidy wiring/master box inside but BB was very slow. We pulled back their old garden shed to reveal the incoming line which came in under the driveway, up the garage wall to a circular BT box, then usual four-core cable under a window sill and through the wall into the house. It was so old that the insulation crumbled when I pulled it, exposing the bare wires. BT replaced the lot from the incoming line to a new master inside the house which made a vast improvement. Mind you, I still wonder about the old line still under the driveway but it works so I leave well alone. Good luck!

Hi Robertos, apologies, I had read that post, but somehow my brain skipped over it concentrating on what I thought I knew about.

Yes, I see what you're saying.
I'm pretty certain the socket I was working from does feed from the decrepit one. I can follow that cable. The decrepit one is on the floor in a hallway in the middle of the house. Not easy to comfortably poke about in.

The pristine one is where the cable comes into the house.
Actually, I think I need to visit again and poke about in these various junction boxes, and maybe photo again with all the wires exposed a bit clearer.
The pristine one does confuse me on looking at it again.

So, yes, I'll visit again and pay close attention to the wiring details this time.
Thanks for that again.

Thanks Malwaremike.
From that pristine box which is immediately inside a window frame, the cable runs up the outside wall, then overhead a good distance to presumably a pole at one of the neighbours.
I'm going to visit again, but other than running a ladder up beside the stretch just outside the window, I doubt I could easily inspect the outside cable any more. Anyway will try.
Cheers again.

It's likely a waste of time putting up a ladder to look at it, as anything wrong here will need to be rectified by BT/Openreach.

The cable that comes through the window that the orange and white cores are visible in the photo should be the end of the drop wire from the pole. It would be best if a new master socket could be installed at this point, then new internal cable installed direct to a new socket where the router lives.

It is super confusing as the colours do not marry up the whole way...

For example you have what appears to be solid orange and solid white leaving the new junction box, so why do we not see the same at the old junction box... I see solid orange and white/blue (not solid white) at the old junction box. So now I'm left thinking where does that solid white cable (on the new box at the window) get changed out to a white/blue cable... If it went all the way straight to the old junction as you say, we would see it there.

I think your understanding of the way this line is setup is not 100% accurate, there is more to this story. You really want to be able to follow these lines properly and identify the mystery second socket also.