Ok, lets take another look at this issue.

Have you got any stats from when you were originally connected to Sky or once DLM had completed? Most people won't have them recorded, but worth asking.

Have you tried changing the Micro-Filter? These can and do go faulty over a period of time. If you are able to change it then this would be good.

It might be worth installing a Filtered Faceplate on your Master Socket in the longer term.

Could you also try plugging into the test socket, located behind the faceplate on the master socket and posting your stats from there please?

When doing this test, could you also ensure that any extension that you may have are all dead.