Q: Wifi Zone Shrunken after Airport Extreme and Airport Express Updated to Version 7.6.4

Same result here on a Airport Express 802.11n (A1264). Basic config is to extend the (hidden) Wifi network from a brand new TC (firmware 7.7.1) with MAC address filtering (no Airplay activated). On firmware 7.6.3 everything at the Express was working as designed. After upgrade the to 7.6.4: for some minutes everything working like charm. After that time, no connection anymore - the Express is no longer extending the Wifi - and the ugly thing: the Express seems to look correct from client side (is also green LED) - but when the client is trying to connect, nothing happens - but: as long as the Express is powered on, the client wants to connect to it (which doesn't works). After poweroff/poweron of the Express: everything is working again for some minutes - after that, same issues as described. After rolling back to firmware to 7.6.3, everything is working as designed again - no issues since then.

And: on new Express (802.11n 2nd gen (A1392) with AirPlay activated and in network extending mode): after upgrading to firmware 7.6.4 music drop outs occuring after some minutes of playing content (via Airplay from a iphone 4). First, some drop outs...then stop of playing music at all - i had to reconnect airplay (choose internal iphone speaker, hit play, and then choose AirPlay device again and hit play again)....but: networking extending was still working as designed all the time. After downgrade to firmware 7.6.3, everything is working as designed again....no issues.

conclusion: in my opinion, firmware 7.6.4 has some general problems on different device types and using old firmware version 7.6.3 produces less issues.

BTW: i didn't tried that much with: reset back to factory defaults and rebooting and reconfiguring the devices and trying again because in my opinion: the piece of hardware simply has to work stable and reliable without playing around for hours and hours - if i would like to spend hours and hours in not working hardware, i wouldn't have bought devices from Apple.

Same result here on a Airport Express 802.11n (A1264). Basic config is to extend the (hidden) Wifi network from a brand new TC (firmware 7.7.1) with MAC address filtering (no Airplay activated). On firmware 7.6.3 everything at the Express was working as designed. After upgrade the to 7.6.4: for some minutes everything working like charm. After that time, no connection anymore - the Express is no longer extending the Wifi - and the ugly thing: the Express seems to look correct from client side (is also green LED) - but when the client is trying to connect, nothing happens - but: as long as the Express is powered on, the client wants to connect to it (which doesn't works). After poweroff/poweron of the Express: everything is working again for some minutes - after that, same issues as described. After rolling back to firmware to 7.6.3, everything is working as designed again - no issues since then.

And: on new Express (802.11n 2nd gen (A1392) with AirPlay activated and in network extending mode): after upgrading to firmware 7.6.4 music drop outs occuring after some minutes of playing content (via Airplay from a iphone 4). First, some drop outs...then stop of playing music at all - i had to reconnect airplay (choose internal iphone speaker, hit play, and then choose AirPlay device again and hit play again)....but: networking extending was still working as designed all the time. After downgrade to firmware 7.6.3, everything is working as designed again....no issues.

conclusion: in my opinion, firmware 7.6.4 has some general problems on different device types and using old firmware version 7.6.3 produces less issues.

BTW: i didn't tried that much with: reset back to factory defaults and rebooting and reconfiguring the devices and trying again because in my opinion: the piece of hardware simply has to work stable and reliable without playing around for hours and hours - if i would like to spend hours and hours in not working hardware, i wouldn't have bought devices from Apple.

Yes....  This is really a problem.  I restart my computer, Airport Extreme, and still it continues jump between "Wi-Fi: On" to "Wi-Fi: Looking for Networks".  Come on Apple, did this update screw us all on Airport Extreme.  It seems to have reduced the signal strength as well, and it comes and goes.  I too have Comcast Internet.  I used to get a full signal from the Airport Extreme, now I only get one or two bars.

Last weekend, I travelled to my wifes sister where I had installed a Airport Express 802.11n (A1264) at least 2 years ago. During the visit before, I had upgraded these Airport Express to firmware version 7.6.4. On the last visit a saw, that the Airport Express changed (without interaction) from normal operation (green LED) to error (blinking amber LED) and was not accessible anymore from ipad/iphone "AirPort" utility. After power-off and power-on the device, I downgraded the firmware to version 7.6.3 - since then: problems are gone. BTW: this Airport Express is running in Wifi-client mode only and just AirPlay is being enabled.

Mr. Goose: This reply refers to the blinking amber light after upgrading to 7.6.4.  I experienced the same thing, and after looking into the problem, I found that the cause was manually setting the channel for broadcast.  For some reason, my AE Gen 1, which is running in bridge mode to a Gen 5,  didn't like Channel 8 and the amber light was reporting that this configuration was no longer compatible (despite the fact that it worked fine previously).  I switched the configuration to Automatic Channel selection and the AE went back to solid green.  Go figure.

-Brad