There is one problem here. As the door fitters buried the junction box, it will be a chargeable job. Sorry, order of £160.00 + VAT.

Can we try and look at this from another angle with a view to improving the BB signal.

Is it the first socket in the house that you used to connect the router to, or are there other phone sockets and is the router connected to one of those?

If this were my home I would cut the external cable, unclip it from the wall and run it into the loft where a joint could be made to new internal wiring and the master refitted where required.
The problem with door fitters/ double glazing installers is that sometimes they get clever and remove the joint box altogether they just twist the wires to form the joint and slap some plaster on top. This avoids buiring the box. The joint then corrodes and leads to line noise. No amount of rewiring or anything will improve BB performance untill this joint is delt with.

Assuming that is the problem.

I must council against touching BTOR's wiring. It is theirs and they do get upset if it is altered.

It has a wooden door frame.

Thats good. A metal frame can cut into the insulation of the cable. What are your line stats like?

ADSL Link Downstream Upstream

Connection Speed:

Down - 3715 kbps
Up - 939 kbps

Line Attenuation

Down - 50.5 db
Up - 25.5 db

Noise Margin

Down - 9.1 db
Up - 6.0 db

Yes I see your point, and understand why you want to check your wiring. You need to get the joint sorted at the front door

In reply to a post by yamaha22:

The outside cable runs down the wall on the outside of my house and goes in beside my front door.

The joint between the cables must be inside the wall.

Inside the junction box I assume it would be a simple joint nothing else.

If so it should be simple to reroute the cable with a new junction box and cable for inside.

Is there any very high quailty cable and junction boxes you can recommend?

Im trying to improve my ADSL2+ connection, im getting about 3.7 mb down at the moment.

I doubt whether it will make any difference at all. Recently BTO changed the cable from the pole to my house, and they also re-sited the master boxes (I have 2 ADSL lines). The old installation had the wire from the pole going up to the loft, where it was coiled in a loop, and joined to another cable which went to the master sockets. I thought that the replacement of this cable with another continuous one which was half the length would make a big difference, but it made no difference at all.