Q: Why am I seeing "device not found" AirPort Admin?

Do you have Back to My Mac configured on your AirPort Extreme? If so, disable it.

This issue has been rampant over the last few days. We are all awaiting a response / fix from Apple.

Great question!

You can still access the base station by using the File > Configure Other... option in the AirPort Utility menu bar. Just enter the base station's router IP address (the default is: 10.0.1.1) and the base station administrator's password (the default is: public) to access the base station.

Well, turning off BTMM doesn't help managing remote Airport basestations, especially when Manage over WAN is not turned on (as per good security practice).  Using BTMM to a remote OS X system works to access a remote Airport basestation if, and only if, there happens to be a remote OS X system to connect to and run Airport Utility.

This problem occurs with Airport Utility 6.3.6 and 6.3.7 on 10.11.6 and 10.12.x and with Airport firmware 7.6.4, 7.7.3, and 7.7.7.  Additional symptoms include disappearance of printers shared using an Airport Extreme. 

However, screen sharing access to remote OS X systems remains viable. I have tested using Airport Utility on systems accessed through Screen Sharing and found identical symptoms.

My conjecture, based on geographically diverse systems and software versions is that there has been some change in apples wide area bonjour service which is not successfully communicating with the Airport basestations. This would mean that Apple is the direct source of the problem, not any user boxes.

Thanks it worked for me.  I guess we keep checking back to see when we can turn BTMM back on.

What you say is true. However for some, turning off BTMM will get them access to their AirPorts until the issues is resolved.

Good to know that it’s not only me and that it was not my ignorance that broke my network.

Thanks

Add me to the list of people with this issue.

F me.

I'm having this issue too. Just tried configure other, default 10.0.1.1 (password: public), and the dialogue just spins blank, trying to read settings and eventually errors out.

Tesserax: did you imply to just use the default IP, or actually hunt down the actual IP of my base station on the network?

Have you tried the suggested workaround, turning off Back to My Mac? There is also information on how to access your AirPort if the AirPort Utility doesn't see it.

I also found that if you unplug the power cable from the AE and then plug it back in that it will show up again temporarily in Airport Utility on my iMac allowing access to the edit functions from there. Just hit the edit button quickly once the AE re-appears because after about 30 seconds to a minute it will become unaccessible again and show up like the screenshot that Brian added above.

It is now fixed for me.

@pjgois - Fixed when Back to My Mac is ENABLED?  Or disabled?

Fixed while “Back to My Mac” enabled. The problem only lasted for 2 or 3 days. I changed settings now and then to check if the problem persisted and then, one time, after enabling “Back to My Mac” it all kept working fine.