Hi jangodoggy,
I'm also trying to troubleshoot a problem related to Apple and my 5GHz signal that mysteriously appeared three nights ago. In my case, I've had the 5GHz channel working smoothly for about 3 years until it disappeared on all our Apple devices. It became visible again just as surprisingly, except, the password was no longer being accepted. I'm still working on this and have already performed a hardware reset with no positive results. See post "Incorrect Password"
My question is to you is, on the devices where 5GHz is visible but not logging in - what error message on the device do you get when you attempt to log into the 5GHz? Have they performed any OS updates recently?
Is your setup default? Meaning it pretty much ran straight out of the box without much configuration tweaking?
Thanks.