The camera does not work
- Black picture: another app holds the camera (Zoom, Teams, OBS), or the laptop shutter is closed / disabled with an Fn key.
- Lower resolution than advertised: the camera is on a USB 2.0 port or the browser chose an economy mode; request Full HD above.
- Low frame rate: not enough light; cameras lengthen exposure in the dark.
Security cameras: RTSP URLs. More: microphone test, speaker test.