I have a Superhub 2 and I've been experiencing the same thing: my devices can see the wifi signal but can't connect properly (the signal strength is fine, but I see the little exclamation mark beside the wifi indicator). I have to disconnect and reconnect, and all works fine for maybe 30 minutes or so, and then the handshake drops again. Last night, even my signal repeater lost connection and couldn't handshake with the WPS signal even when right next to the Superhub. The old off-and-on-again trick with the Superhub seems to have settled everything down, but it might be worth VM having a look at my signal from their side.
I have the same problem - wifi connection looks fine - lots of bars, but when you try to go onto internet on our devices it says the server can't connect. I have to disconnect from the wifi and then reconnect and like other customers, it works for half an hour or so, then goes again. It is happening with all our devices, hence the problem is with the wifi/hub, not our devices.
Very frustrating and I can't get through to anyone on the phone as there is a problem with connecting to the call centres at the moment.