I just came across an interesting situation where the Airport Utility showed a red alert with a „1“ in it, indicating some sort of message or update, but not detailing what it was about – and actually no apparent possibility to do anything about it:
A quick search on Google brought up the idea to use an older version of the Airport utility, which identified a newer version for the Airport to be available, and allowing to update it.
The most im portant part was to find this page, where the author suggests to download version 6.5.1 of the Airport utility. This version does not work by itself on El Capitan, so he has put together a launcher script that will make it work. You can download both from his page. Unpack the zip file and double click on the launcher:
This should launch the older version of the Airport Utility, allowing you to run the update:
You’ll immediately see the new version has been installed in the newer utility:
As you can see, the older Airport utility program is very much more useful than the newer one – so in case the original author’s file should become unavailable, feel free to download it from this site and, of course, use at your own risk.