DIAGNOSIS The app and the node's status are out of sync. The node is likely functioning, but its connection to the Deco cloud service is disrupted.
FIX Reboot your main internet gateway first. Then reboot the main Deco unit. Wait 5 minutes. The app should correct itself. If not, force-close the Deco app on your phone and reopen it. The status should update.
IF THAT DIDN'T WORK There's a local network conflict. Log into your main internet router's admin page. Check the connected device list. If the Deco units are listed there, the mesh is fine. Ignore the app error. It will clear within 24 hours.
HEADS UP A solid blue light means the node is operating normally. This is an app/cloud glitch, not a network problem. Your WiFi is probably working. Do not factory reset based on this message alone.