Accessing the UniFi NVR The UniFi Video configuration portal is accessed by using a web browser. There are two ways to access the portal: • Ubiquiti Device Discovery Tool For users with a. Ubiquiti Device Discovery Tool is an app allowing you to discover and see Ubiquiti devices on your local network. You can filter those devices by type (UniFi, airMAX, EdgeMAX.) or by using search.
I have had links go down in remote buildings that feed the backbone connection to the Ubiquiti server controller software. That causes a disconnect to show.

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Merely correcting the downed link causes that AP to be recognized and it reconnects to the server and becomes available.
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I would think either you can bad communication to the AP or the AP itself has an issue.
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Mine will flash GREEN when it is disconnected. You said yours is yellow?!? Yellow (I THINK) means it's not associated - or as Ubiquiti says 'adopted'.
Putty
Deacon