Hi the guest network is setup through the HUB (3), so its not anyone else's wifi.
I have tried resetting the hub and restarting the hub on numerous occasions, I just cant connect to the normal network wothin the hub with either of my mobile phones. I can connect with two other laptops without any problem
I'm slightly surprised that a guest SSID appeared without the Hub3 being deliberately set up for it. It certainly didn't happen with mine. As to the laptops connecting but not the phones that is also strange. Is the Hub broadcasting on both bands, and are the phones set for both bands? When you reset the Hub, was it a full factory default?