Hub 2 working fine with wired connections and several android / Windows based wireless devices. Within past week two of the four android devices we use have lost the internet connection via WiFi. No problem with signal strength on 2.4 and 5. Wi-Fi apps on affected devices report no problems. Both affected phones are different makes and android versions but share same Google account but unaffected are under another name. I have no idea what's going on!
Are those affected devices actually connected to your wifi network, or they just "see" the network but cannot connect ? If they're connected, try to "forget" the network and reconnect again (it will prompt for password again), and make sure that DHCP is active on those devices, so it will help to assign IP addresses properly. Please post back more info, so we can try to resolve it.
P.S. I assume, that you've tried restarting your devices (includin superhub) already...