If you got a MK3 faceplate you could connect 100% copper cw1308 cable (or cat5e) to it's A&B terminals and run that unfiltered feed through to a dedicated rj11 socket in the other room. The router could then be connected to that socket via a rj11 cable. If you did that it would still be possible to use a filtered voice extension from the NTE5a/MK3 to a phone connected to the original phone socket in that room.
Good luck.
OK, one more question if you don't mind. I have fitted a Mk3 Faceplate and am very pleased to report that it has worked perfectly, just as you described. The phone is now back in the other room on the extension, with no loss of internet speed with the router at the master socket.
I'm more than happy to keep the router at the master socket, but I might just go the whole way now & give the router a try on a dedicated RJ11 socket in the other room - You mention running cw1308 cable from the A & B terminals of the Mk3 - could you advise which terminals they would connect to at the other end, in the RJ11 socket?
Many thanks
Edited by alfiecat (Fri 25-Feb-22 22:17:23)