Hi gazy007,
I realise you posted this a while ago and hoping you’ve already found the answer you needed, but just in case and for other members who might have, with the Hub 5 you can get port forwarding setup guide here.
As for the BT hub/router only allowing certain IP's through, they do have have this cpapability, you would need to look at replacing it with a different hub/router if you want this functionality.
Regards
Markp