Hello, I have a Aiport Extreme with 802.11ac that I got last summer. It has worked great up until about a month ago. All of the sudden it has started not allowing clients to connect to it. You can select it from the WiFi menu on a Mac or an iOS device, it will ask for a password, but when I type the correct password it will reject it. What is really strange is that this seems to only happen in the evening and usually goes away the next day. I have an 802.11g router from AT&T which will continue working when the Aiport is experiencing this issue. Here is what I know and have tried to resolve the problem: Restored the Aiport Extreme to factory conditions. I have even downgraded the firmware and then upgraded it again. I have tried changing channels. I have used a WiFi scanner and the 5GHz band is pretty clear. The 2.4GHz band is congested. I have tried using separate 2.4 and 5GHz netowrk names. I have a lot of wireless devices, including some WeMo switches and a Sonos system. I have disconnected every wireless piece of kit here (including the AT&T router), then tried connecting with a single iPhone. I have tried using it with password protection disabled. I am completely stumped. The only explanation I can find is interference from some outside source. I'm in an apartment building and perhaps someone is coming home from work and turning something on. But why would this affect the 2.4GHz band on the Airport and not the same band on the AT&T router? The Airport is extremely limited in its wireless settings. So I cant try disabling ac and trying it with n alone, not can I change from 80MHz to 40 or 20MHz bands. Does anyone have any ideas?