These routers are all fairly new and as i live in an old house with very thick walls need these routers fir the wifi around the house. The only area that my need replacing in the power adaptors. Do you think this will solve tge problem?
Whether the routers are old or new they will not do what you want them to do. In addition if you need two ring mains then that brings other questions into play regarding IEEE 17th edition regulations, it could be that the Multicast packets are being swamped by mains noise as they traverse the powerline adapters. If that is so then you will need to find another way to achieve your aim. Either way it seems to me that your problem is down to your local network and not your BT kit