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Summary: In my neighborhood, there are about 20 WiFi networks visible when I click the WiFi symbol on my MacBook's top menu. Needless to say, WiFi is wonky . . .
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> Corey J. Mahler automated a workaround, which is described and [http://coreyjmahler.com/2013/10/24/airport-utility-5-6-1-on-os-x-10-9-mavericks/ can be downloaded on his website]. If you do, I encourage you to send a small donation to him. Scroll down on that page and click the green dollar sign. He's been keeping this solution in the air for multiple years now.
In my neighborhood, there are about 20 WiFi networks visible when I click the WiFi symbol on my MacBook's top menu. Needless to say, WiFi is wonky and unstable. The usual advice of a great WiFi deployment is: multiple access points (APs) with the same SSID, where you dial down the transmit power so you cover only the exact area for that particular access point.
It's thus a damn shame that the latest version of the AirPort Utility (version 6) does not allow you to influence the transmit power. The older versions did provide an option to do so, but it doesn't run anymore on the latest versions of OS X.
Corey J. Mahler automated a workaround, which is described and can be downloaded on his website. If you do, I encourage you to send a small donation to him. Scroll down on that page and click the green dollar sign. He's been keeping this solution in the air for multiple years now.