Mini boxes won’t connect

[DSN6]

After a long wait and some traumas with Sky and OutOfReach along the way, I've finally been upgraded from and old Sky Superfast copper connection to Sky Fibre 150.  This includes the the latest Sky Max Hub and Max Pod. 
All installed and up and running today. Speed test (via OpenSignal) shows 149mbs Down and 29mbs Up which is what I expected.

However, despite promises from Sky that the new setup would eliminate occasional  dropout issues with my Q mini boxes, it appears to have made things much worse! Despite following all of the advice in this site about rebooting all of the boxes and resetting network connections....neither box will stay connected on the network. I thought I'd solved it but when I switched the boxes back on, it came up with an error message and no connection. I've gone through the whole process several times and have given up now. 

WiFi is working elsewhere in the house and the connected TVs are connecting fine. It's just the mini boxes that won't work. 

Main Q box is less than 1m from router and connected via Ethernet. Both 2.4 and 5 are off on main box (as advised by Sky engineer).  Mini boxes are in upstairs bedrooms with no access to cat5 so rely on wireless. 2.4 and 5 are on. 

Any help and advice gratefully appreciated. 

[oldfella]

Hi @DSN6 

First try rebooting the main Q box and then when this is completely back up and running reboot the minis.
To reboot press Standby on your Sky Q remote (if the box responds to the remote), and then switch off and unplug at the mains.
Wait at least 30 secs and then Plug back in and switch your Sky Q box back on at the mains.
Wait for the on screen instructions to disappear and the front led to turn Amber. Then wait for 30 secs before you press Home on your Sky Q remote or if this is not working press the standby button on the front of the Q box (Amber led)

note: some features may take up to 5 minutes to return.

Reboot the minis as above.
If the mini still does not connect try a Network Reset on the minis. Start with the one nearest to the main Q box
Network Reset found in mini Home - Settings - Setup - Network.
Highlight Status and then select Reset on the right hand side. Follow instructions to WPS with main Q box.
You will be asked to press the WPS button on the main Q box (not the mini as the Network reset will start the mini WPS automatically).

If you are on Sky Broadband and the Router is nearer to the mini than the main box then you can try pressing WPS on the router instead of the main Q box. If you do this make sure you press the Sky router WPS button and not the router reset button. If you have the new Sky Max router then you need to connect the WPS to the main Q box.
If you get the first mini connected then for other minis use WPS on the nearest Q device (main Q box or Sky Router (not Sky Max) if on Sky Broadband or previously connected mini).

Failing all of the above you may need a Sky Q WiFi Booster to position midway between your main Q box and the mini and you will need to contact Sky directly.