Sky Q mini boxes (x2) consistently losing connection to main Sky Q box.

[Bazzer1]

Almost every evening our 2 mini boxes bring up identical messages showing loss of connection to main Sky box. Through the settings menu on each box they both connect without problem and work correctly  during the evening. Next day both display the same message showing they are not connected to sky box. I have tried rebooting the main box cutting power to both box and tv and delayed restoring power for 10 minutes but mini boxes continue to lose the connection. Also tried rebooting mini boxes but problem persists. As both mini boxes have the same issue the main Q box seems to be the issue. Not a WIFI issue as we have arranged for a BT engineer to check signal strength at each mini box location which is good. Any suggestions as to curing this annoying habit?

[Jocky1]

We had a 'technical fault' five days ago. All boxes went down. We managed to get main box and 1 x mini box working, but the other 2 x mini boxes freeze the TV screen - one has the usual opening screen, but it is frozen with a Sky advert going on in th small top left box; the other shows a 'settings' screen, but this is also frozen. Anyone have any ideas how to get these boxes working agaiin, please?  Jocky