Diagnosis
This is almost always a network handshake failure, not a dead camera. The camera is powered but can't talk to your router, usually because of a weak WiFi signal or a router setting blocking it.
How to Fix It
First, power cycle the camera and your router. Then, in the Reolink app, go to the camera's settings, then Network > WiFi. Tap 'Reconnect' and re-enter your WiFi password. If that fails, move the camera (or its WiFi antenna) physically closer to the router and try the reconnect process again. The 5GHz band has shorter range, so if you're far away, force it to connect to your 2.4GHz network during setup.
If That Didn't Work
Your router might be isolating client devices. Log into your router's admin page and look for settings like "AP Isolation," "Client Isolation," or "IGMP Snooping" and disable them temporarily to test. Also, ensure your router isn't using a WPA3-only security mode; WPA2/WPA3 mixed is safer for compatibility.
Heads Up
The camera's status lights can be solid even when it's only getting power from the PoE injector but the data connection is bad. If using the included PoE setup, check that the Ethernet cable is fully clicked into both the injector and the camera's weatherproof port.