I've seen the same thing onour Samsung S4 Mini - fine for a while then just won't connect.
I'm currently trying wifi on mode 3 to see if the problem still occurs.
I did notice when the problem happened my iPhone 5C also struggled to connect, but did manage it in the end. Whereas my Motorola was fine, though it was using 5Ghz and the others 2.4Ghz.
Never had the problem on the old HH4 - 2.4Ghz and 5Ghz were both fine.
I've had problems with 2 BT Smarthubs after upgrading from BT broadband to BT Infinity 1. Both stopped working on WiFi after 24hrs due to DHCP errors. Got worse so could only get one device to connect.
BT technical support sent out a new Smrthub, did exactly the same, stopped allowing connections after 24 hrs. I checked the event log, there was a firmware update on the second box just before it started failing. The Firmware code is SG4B10002214F dated 22/6/16. This cannot be fixed by a factory reset. Anyone else had similar problems?
Waiting now for a Home Hub 5 although I'm not that confident.
Previously had BT broadband with a Home Hub 4 with no problems.
From the Home Hub 6 home page (http://192.168.1.254) select Advanced Settings then Wireless (or try http://192.168.1.254/0000012803/gui/#/advancedWifi) then scroll to the bottom of the page you'll see a 'Wireless mode' option.
A number of people reported Wifi problems on the forum with the SG4B100021F4 firmware. In all the cases I've seen they've reverted to HH5 or some other router and the problems have been resolved.
It should. From what others report, when they've had problems with connecting to the HH6 wireless, replacing with a HH5 has resolved the problems.
Best of luck.
I had similar problems with devices continually connecting and disconnecting, eventually breaking my nest thermostat. The problem moved to my tv with constant connected/disconnected messages. On setting the router to mode 3 the problems have gone and I haven't encountered any performance issues.
Lastly, full marks to nest for replacing the thermostat free of charge and sending an engineer to install the replacement.