I have an AirPort Extreme 5th gen came with 7.6.1. No problems at first about 6 months in after a few updates to latest firmware the wifi signal shrank and wifi and wired speeds dropped considerably. It seems like every router I get performs great then issues develops
I took it to apple store and they tested it and it ran fine. I got it home and the issue started again.
it appears to be something wrong and I wont buy another apple router went to an asus and its got QOS and is making my internet shine again.
I loved the ease of use at first but after reading this thread I'm buying a warranty when I get any new router and just replacing when signal issues become a problem.
I live an hour from the apple store so to drive back down there even if they gave me a new one wouldn't be worth it.
a person at best buy was saying the power supply was really close to the antenna on the router I have and could cause heat issues???
Just thought it would last longer.