Unable to connect to BT Home Hub

My Video Doorbell 3 cannot connect to my BT Home Hub. I've tried numerous times, rebooted the router, moved the devices so they are literally next to one another. This is the second unit I've tried so clearly there is an issue with the hardware itself - I've not had any other issues with devices unable to connect to the WiFi, including numerous laptops, tablets and smartphones. I can only assume the WiFi capability of the doorbell is simply not fit for purpose. Obviously many people do not have a problem - but the BT Home Hub is hardly some obscure piece of equipment so I am amazed Ring are allowed to sell this in the UK. The fact that there is no customer support apart from this community just adds insult to injury.