Had ADSL2+ for a 10 months without any problems, connected solidly at 23Mbs throughout all of that time as i'm very close to exchange. However, last 2 months the max I can connect is 14Mbs and my router reports the internet connection regularly drops (usually overnight, around the 1am time) and that is it altering Db levels to maintain connection. As such I have been put into a banded profile a couple of times. (At present on a 12Mbs profile).
I have no noise on the line, and I have replaced all of the following: Filters, all cables and the Router itself. I only have one master socket in the house so I contacted BT who sent an engineer out. He tested the BT line back from the master socket and sent diagnostics to whoever to analyse but it came back reporting there is nothing wrong with their line to my house and there is nothing more they can do; it must be my equipment.
Next step I decided to take the faceplate off the master socket and leave the router directly accessed to that. I left it like this without touching it for nearly 4 weeks. Nothing improved, router regularly shows disconnects on the wan, still reports bad line and speed never improved.
So what do I do now? BT don't want to know and say its my equipment. Please don't say leave it and it will improve, I've left it for nearly a month!
Various test results and stats attached. (The wholesale result was carried out with a wired connection direct to master socket)
you appear to have done everything you can to prevent the disconnections - test socket, new filter, new cable - and as quiet line test ok then you need to get engineer back leaving it will not magically fix itself