The issue is now resolved, thanks. Looked it up on Youtube as 4 calls to 1st Line offshore agents at VM couldn't work it out.
For anyone using Hub 3 and getting 'Wifi drop outs' then make sure you name each network SSID identifying the 2.4Ghz and 5Ghz SSID separately. Some devices use 2.4Ghz spectrum only, so will only see the 2.4Ghz SSID you setup when searching for the network. All other devices will see both networks, in which case, connect those to the 5Ghz SSID. This should make your connections more stable.
This can be done via the admin pages > wireless > security.