Thank you for the suggestion.
I tried that and I tried rebooting the modem, but I still can't see the booster.
I also connected the extender to the hub via ethernet cable in the hope that they'd gain knowledge of each other, but once disconnected the booster just keeps flashing.
Does it matter that the ssid is different to the one originally installed?
Do they come pre programmed with an ssid to attach to? Is there any way to log in to the booster to get help?
How do I get help if we cannot solve things here?