Ring Doorbell 2 Live Not Activating

I recently installed a Ring Doorbell 2 and it worked ok the first day, but today the Live view will not activate. The router is about 4ft away. RSSI 51 Upload and download speeds both over 18mbps. I've reset the router and tried the Live Activation on 2 mobile devices in the house, but with no luck. I've turned off the wifi on my phone and tried again with data - no luck. The doorbell does record videos of motion and calls, and I can see these ok in the app, so it seems the wifi connections are ok. Can anyone please help with why the live activation is not working? Thanks.