What BT hub were you using before the switch over. Unless I am mistaken the "newer" Homehub 5 has a WAN port (red colour) for FTTP and as has been pointed out the Smarthub has Port 4 as a WAN port if you switch it on in the hubs settings if it has not already been turned on.
BT-Home-Hub-5-Self-Install-Guide.pdf
4043 BT Smart Hub-A SI FTTP User Guide 084318 v2 1.pdf
Yes, I can confirm that. (I've still got a couple of Home Hub 5's. The amount of junk I've got. I really must have clear out). Both the type A and type B have WAN ports.