Shortly after the wireless controller is closed or the computer that the controller runs on is shut down, all SSIDs stop broadcasting on the UAPs at the configure site(s).
Possible causes / recommended actions
This usually shouldn't happen but in some scenarios it seems to. In some cases the default gateway may get incorrectly detected.
There are 2 possible solutions to this (you only need to perform one).
The first method involves going to Settings>Site and under Uplink Connectivity Monitor, choose custom IP, manually enter your gateway IP (or another static LAN IP) then Apply the settings.
The other possible solution is to disable the Uplink Connectivity Monitor. Do note that this is also tied to wireless uplinks, so if you are using wireless uplinks you would want to define the custom IP instead.
To disable the Upink Connectivity Monitor you would want to go to the above location, uncheck Uplink Connectivity monitor and then apply the settings.
When changing this setting it will trigger a site wide provision so keep that in mind.