A camera that responds to a "ping" command but refuses to show video often has incorrect gateway or DNS settings. AXIS Camera Station 5 - Troubleshooting guide
Automated bots look for IP cameras on standard HTTP/HTTPS ports. Changing these forces a scanner to work harder to find the interface. Go to > Network > TCP/IP > Advanced .
This comprehensive guide covers how to repair the physical live stream and how to lock down your network to remove your camera from public view.
If you have tried all these steps and the live view is still not working, consider a hardware fault. For some older models like the Axis 213 PTZ, a "NO VIDEO" error in the corner of the preview window is a known symptom of failed capacitors on the video module's interface board. In such cases, repairing or replacing the hardware is the only solution.