Okay just to remove the confusion are you talking about BT Halo 3 or the SmartHub 3 the two are not the same, and depending on your existing (Unifi) equipment (which is?) it could make an awful lot of difference!
If it is just the SmartHub3 then you'd usually be better off with the Unifi router plugged directly into an ONT (white box on the wall) and using PPPoE credentials, that's provided you you have full-fibre. If you don't have full fibre and are using the SmartHub to connect to an xDSL connection that come in over the phone line that's a whole other conversation - and Halo would probably (though not necessarily) be a bad choice!
Whole house, garden, garage and half the street covered by a Flint 4 - WiFi 7 router
