I have set up two kits as follows.
1) BT SmartHub 2 with a full fibre broadband connection
2) SKY Q main box - lounge
3) SKY Q minibox - kitchen
4) SKY Q minbox - garage
Very easy to do and 1, 2, and 3 are stable and I can enjoy perfect TV in the kitchen and lounge with none of the problems I had before over WiFi. Great!
4) seemed to be equally good. The Powerline adaptor is plugged into a mains socket with nothing else attached. All lights on and solid. However the SKY Q mini initially connects OK to the main box and then after a couple of minutes it will freeze. If I restart it then the initial response is good and service is restored but again freezes after a couple of minutes. As 3) is solid then I am thinking it is something to do with the electrical cable run and installation in the garage. I'd like to try and diagnose this - does anyone have any suggestions on a) diagnostics I can run on a Mac and b) any suggestions on fixes?