Internet access stopped. Router (VR600v2) showed no internet on basic info tab but connected on detail tab.
Rebooted router - came back at a much slower connect speed and a high SNR. Then it dropped.
Then it came back at 22MB and a negative SNR
Then it dropped to 0 across everything and indicated there was no line connection
Checked phone - silence, plugged phone into master socket ... silence. Plugged filter back in, phone still silent and router showing no connection
Then a few minutes later it all came back fine.
I assume a BT engineer somewhere unplugged something he shouldn't have.and then realised what he'd done.