Q: Airport Extrem "Device not fount

This is a common bug with the El Capitan, Yosemite, Mavericks and Mountain Lion operating systems that Apple has not been able to fix reliably. It's usually not all Apple's fault, though.

Try a complete network power cycle. That would mean.....

Power off all network devices.....modem, AirPorts, computers, printers, etc.....in any order that you want

Wait a minute

Power up only the modem and let it run 2-3 minutes by itself

Then, power up the next device connected to the modem, which might be the AirPort Extreme

Keep powering up devices one at a time about a minute apart until the network is back up

Keep an eye on the network

If the issue continues, we will need to check and probably change the IPv6 settings on your Mac and the AirPort Extreme. The reason for this is that most Internet Service Providers are trying to introduce and incorporate IPv6 technology into their systems.....and while most ISP insist that this should not cause any disruption with connections, this has not be the case with a number of ISPs.

I encountered this problem yesterday with 4 devices - a 2 time capsules, an extreme, and an older airport. The older device with visible in airport utility, but this was because it was remote and creating its own network, albeit with the same name as the network created by the other 3 devices. Wifi was still working and there was internet access, but no access to shared disks or the ability to access these devices via the utility. After various playing, I found that it appears to be related to having an account signed in on the base station to enable back to my Mac.

I unplugged all the devices bar the own acting as the gateway to the internet and performed a hard reset on this device.  Then set this up again and restarted. Once this was back up, I then did a hard reset on any other devices and used them to extend the network. (I found that if I tried the reset with the other devices active it might try and extend the wrong network or it would get confused by the other devices.

If you need any help, just let me know.

After various playing, I found that it appears to be related to having an account signed in on the base station to enable back to my Mac.

The vast majority of users who are having problems with "disappearing" AirPorts do not use Back to My Mac at all, so while BtMM might be involved in your case in some way, it can't be the issue for users.....like me....who don't have it enabled at all.

What I found from using iNet network scanner from the App Store, is that the devices were still being given a physical IP address on the internal network, but that none of the services were being advertised on the network - no AFP SMB etc. The first step has to be able to get one stable base station. The only way that I could achieve this, after trying powering things on and off, was to do a hard reset on the devices which then allowed editing of the settings in the airport utility. It was with great reluctance that I took this step, knowing how much time it would take to getting everything back up, but the hard reset was the key for me. This naturally removed any BtMM accounts from the base stations. This did also change the IPv6 settings, but it was only adding the BtMM credentials that caused the problem to return for me.

Resetting an AirPort base station FAQ - Apple Support

Thanks for the info, but the question remains about what to suggest for users who have the "disappearing AirPort" issue, but do not use BtMM at all.

If TLP Paul is using BtMM, then your tip might help. Hopefully, he will post back to clarify.

Ha sido de gran ayuda sus comentarios.Gracias

I have been having this problem today and I can confirm that in my case removing all iCloud accounts from BTMM on my AEx has resolved It for me.

I had this problem after using Airport Utility to set up a new AE today.  I used the option to 'replace existing device' and it seemed to work, copying the settings and then restarting.  After I power cycled the modem, network devices came up (I have 'extended' network routers too) and I was connected, however in Airport Utility the new AE was not found/not shown.  I did see it as my primary router in iNet (as mentioned by one of the other posters). I powered off the other routers, so only new AE was on and used my MBP to connect to it via wifi OK, but still not shown in Airport utility.   I called Apple support, said that because I had a more complex setup (using other routers to extend network) that it needed to be set up manually, so I needed to do a reset and set it up again.  There should have been a footnote in the Airport Utility or instructions that stated I should do a manual setup. I also found a support discussion note that said to keep AE names simple, no spaces, short.  The Airport Utility process gave it a 3 word name separated by spaces. If this causes problems why allow the utility to do it. Simple stuff really.

Not to rant much, but I am heavily invested in Apple equipment and have become disenchanted lately due to issues like this.  It used to 'just work'.  Now not so much. I have a brand new iMac with random restarts that they can't seem to solve yet either.  It is getting frustrating like the Windows stuff I left behind....

I have network set for BtMM, I see in this discussion it could also be an issue, will find out when I start my new AE install for the second time.

same error here, resetted everything to factory default and created a new connection. For some minutes the airport extreme is showing up in the utility and can be configured. even a restart does not change the actual configuration. But - if I connect to the HDD at the USB of the extreme, the partitions are showing up for some minutes before they disappear again. In this moment the airport extreme has disappeared from the utility window too. Configuration without reset impossible. Internet access is working and all devices (IOS via wifi and printers and airplay) everything is working fine. in the end I'm not able to access the extreme and the connected hard drive.

It may be possible to configure even when not visible in airport utility. You can do this by directly entering the internal IP address of the device.

1. Go to File and pick configure other
2. enter the IP address and password for the base station
3. configure as normal and update

If you do not know the IP address, you can use iNet scanner https://itunes.apple.com/gb/app/inet-network-scanner/id403304796?mt=12

or if there is one base station only on your network it is likely to be 10.0.1.1 unless you have changed the IP addresses that the base station distributes to either 172.16.*.* or 192.168.*.*

You can easily find this by holding down the alt key and clicking on the wifi symbol in the menu bar this will show your own IP address and that of the router along with other usual information.

1. You can also access any attached drives by using the IP address. Press cmd K  or in Finder go to the Go menu and pick connect to server
2. You can try clicking on browse, but this is unlikely to show the hard disks
3. In the server address box, type afp://10.0.1.1 replace the part after the // by the IP address of the base station with disk

thank you so much seanrik. this is an acceptable workaround until this thing will have been finally fixed.

Finally solved for me: "back to my mac" issue: deleted it from all airport devices.

Thank you so much! This worked for me.