G.INP will certainly help and I think your router supports it.
You may be being affected by your phone wiring so sorting that out will help as well, if indeed there is a problem with it.
Do you have telephone extension sockets in your home? Do you have anything else connected to the phone line, such as a Sky box, alarm, etc.?
Yeah just looked at the specs for my router and G.INP is listed.
I just remembered that I have a spare NTE5 master socket (From a disconnected 2nd line). I guess I could fit that in place of the LJU2 (I know BT don't approve of you messing with the master socket) and then I can fit a faceplate as well.
As for extensions there is only one in a bedroom but it is dead (Tested with the DECT phone plugged in).
I have Sky but it isn't connected to the phone line. No alarm system or anything else that could affect it.
Edited by deleted (Thu 04-Aug-16 21:11:59)