Old Homeplugs and the current range are not compatible. I have 3 (one from modem router, one in to Youview, one in to back up pc) and needed another one as the Panasonic in the far room did not like my bt wi-fi..
I rang Solwise to query this and they confirmed it. My solution was to add an extra switch in the room with the Pana and the pc, and to wire from that switch. Cheaper than buying 4 new Solwises/Homeplugs.
Now I've said that, GG and mixture will try to throttle me over the Internet.