I had a similar issue and resolved it by going into the UI page via a wired connection and separating the wireless bands and also choosing different wireless channels as my hub was not identifying that both my neighbours and my smart hubs were all using channels 11 and 40. This was causing interference and disconnecting my wireless devices.
If you want to see the wireless channels of other routers in close proximity to you are operating on use a laptop with wireless and install a program called inSSIDer. Search for inSSIDer free.
I hope this helps resolve your problem.
After a firmware update, its always a good idea to do a factory reset on the home hub to ensure that the correct default configuration file is in use.
Ok, to give an update on the above...
I tried to do a factory reset but pushing the button on the back of the home hub seemingly didn't do anything at all (no light change or anything)! I did do a power reboot and this worked for around 20 minutes, but then the issues came back.
Ive now split the SSIDs and think I know where the issue is (though I have no idea why it would cause an issue). If I connect devices to the 5ghz band, then they work absolutely fine and I get download speeds of 51 meg (I'm still not sure where the 4 meg has disappeared considering I'm synced at 55, but I get 51 wired too...). When I connect to the 2.4ghz band, then it works for a couple of minutes, then goes again with the same issue before.
I noticed though, that when connecting to the 2.4 ghz, it was also assigning an IPV6 address(es) as well, which it didn't when connecting to 5ghz. I have a feeling it's something to do with this and something around IPV6 that is causing the devices to hang. The other thing to mention though is that the "my devices" bit on the home hub was saying I had devices connected to the 2.4 that were actually connected to the 5, so it was tricky to get to any kind of root cause.
Is there a way of disabling IPv6 on the home Hub? As effectively, the 2.4 range is pointless really whilst it is doing this.
I would try a factory reset - make a note of the changes you have made to the HUB and then do a factory reset by holding down the recessed button for ten seconds. Then re-enter your changes.
- have you setup the network to enable roaming between your two networks (ie same SSID's & passwords) ?
- how have you set up the DHCP server over both of the networks, separate or shared ?
- Do you still have this connection problem to the HH6 if you switch off the airport extreme ?
- Have you tried wireless mode 2 on the HH6?