WiFi max router set up

[Lexter1]

I've had sky broadband for a while. Have upgraded to WiFi max and new router arrived today. Have set it up and light is white and seems to be working BUT the set up assistant says it failed to set up and needs restarting (same happens again) and service checker says everything is working but no devices are connected (even though they are)

what do I do, especially as one of the reasons to upgrade was to ensure a min speed in each room