Hi, unfortunately this is just off the top of my head from about 6 months ago so may not be correct info so forgive me if the info is a bit vague.
But as i use a Superhub 2, i initially had problems connecting to 5ghz frequency as my 5ghz 'Router Channel' was NOT set to 'Auto Compatability' and was set to a channel something around 200, unfortunately i can't remember the 5ghz channel range on the Superhub 2 - i think the 2.4 ghz channel range is about 1-13.
So what i did to get it working was either set the 5ghz 'Router Channel' to 'Auto Compatability' or 'Channel 36', as the Now TV Box seem to have issues finding the higher range channels, and since then i had no problems using the box in a bedroom through walls with the router downstairs.
It might be worth giving it a try if all else fails 🙂
@Lazy56789 as per the comment above, try using one of the lower 5ghz channels. From memory the box only works on approved US channels which don't include the full range we are permitted in the UK.
@Lazy56789 strange yours is not connecting. I have the same set up as you. Virgin SuperHub. Can you go on to the webpage for the hub and just check whether it is set to private?
@Lazy56789 I have both a black box and a smart box. I use smart box more than black box now. Black box tends to be for Iplayer.