If you’re anything like me, you probably have multiple basestations or access points in your domicile which all offer up the same wireless network name (SSID). If things are working properly, any device that joins the network should chose the access point with the strongest signal.
Unfortunately, on Mac OS devices running El Capitan and Sierra you may have noticed your machine defaulting to a connection with a distant access point leading to a terrible signal and getting a terrible signal. Disconnecting from the network and rejoining almost always fixes the issue, but doing the wifi dance everytime you wake your machine from sleep gets really old.
After digging around for a while, I managed to find a fix buried in the Apple support forums. If you have multiple access points all offering up the same network name, every access point has to have exactly the same wireless security setting. If you have some devices set to “WPA/WPA2 Personal”, and some set to “WPA Personal”, you will break wifi roaming in macOS.
Make sure all of your basestations have the same settings and you’ll notice your macs have once again returned to wifi sanity.