My home's WiFi network consists of several Ubiquiti UniFi access points, all serving the same SSID. Mobile devices roam seamlessly from one AP to another.
I have two Rachio (Gen2) controllers. Ordinarily, they connect to the nearest AP and everything works fine. However, if that AP goes offline (even for a short time), the Rachio devices reconnect to a more distant AP, resulting in marginal communication. Even after the nearby AP comes back online, the Rachio devices remain stuck indefinitely on the distant AP.
This situation can arise after a power failure, when the devices come back online in an unpredictable order. If I see that a Rachio has connected to a distant AP, I can force it to reconnect, and it will correctly select the nearby AP. But this is a manual process that I would prefer to avoid.
I have worked around this problem by defining a second SSID that is served only by the nearby AP, and configuring the Rachio devices to use that SSID. This seems to have resolved the issue.
My suggestion is that the Rachio WiFi should periodically check for a stronger signal than the one it is currently using and should reconnect if so. This is analogous to the roaming that mobile devices do. Since Rachio controllers aren't mobile, they only need to do this occasionally so as to adapt to any changes in the local WiFi infrastructure.
(Perhaps this should be a Product Suggestion rather than a Support topic.)