Just got VDSL. It seemed to be OK for a few days, then started repeatedly dropping connection. Fearful that DLM would kick in, I unplugged it and took a look at the socket (a Master Socket 5C, unsure which revision). It seems to be incorrectly wired- there is an extension in the house and I understand it should be connected to the clear part on the left, rather than behind the socket. There were also two wires visible through the hole on the right- white and brown- which had bare ends and were almost, but not quite, touching.
I moved those wires a little further out of each others' way, plugged a microfilter into the test socket, and it seems to sync OK at 79716/20000/fastpath.
Awful phone pic
The faceplate was only a single-socket one, and since my understanding is that the test socket just bypasses extensions connected to the front, the fix might be coincidence/placebo.
In any case, I'd like a slightly neater solution than this. Can I just buy this
(doesn't seem to be possible to buy a faceplate on its own) and plug it in? Given the potential wiring issue, should I expect that to perform better, as well, or worse than microfilter+test socket? I also have a high-quality RJ11 cable ready to go.