OK, well I phoned BT, and they said that because the problem occurs when the router is plugged into the test socket, the problem is with their part of the line, and an engineer is coming to investigate.
Since the issue is not because of something my side of the master socket, I SHOULDN'T get charged a huge callout fee, and I am hoping to high hell that I don't.
(This is for the disconnection when the phone rings issue, I appreciate that the low connection speed IS the house wiring, but not what I want the engineer to sort out.)
EDIT: by the way, I think things are no longer "illicit", the master socket has simply been moved, when we used to have an ISDN setup. The test port in the other room works as expected.
EDIT2: Also, if you use a filtered faceplate that separates internet and phone right at the master socket, is this the same, "interference wise", as plugging the router directly into the test socket, or will dodgy house wiring still affect this?
Edited by joshd (Tue 29-Dec-09 22:47:43)