I'd like to add WiFi coverage for a room in the garden using a TPlink AC1200 range extender in AP mode, connected to a Hub 3.0 via ethernet cable.
When I connect a laptop directly to the ethernet cable it works plus TPlink works in standard extender mode (in house) but when I try to use it in AP mode via cable it states connected but with no access to Internet.
When you connect, try to find out what the router IP address is, also tell your phone to always use the wifi connection (mothern phones will revert to mobile data if they detect that the wifi does not have internet connectivity).
Once you find the router IP, if it is different from the IP of the Virgin hub (your actual router) it means that the access point operates as a DHCP server. Use the reported router IP to access the management page of the AP, then disable DHCP and also make sure that the IP of the actual AP is set within the same range as your home network (best to leave it to get its own IP through DHCP)