The local preview screen displays an error code

1. The preview interface prompts error code -15 or -20

The reason is that the security level of the camera is higher than that of the video recorder. You can modify the private protocol authentication mode of the camera to a compatible mode (setting>system>safety>system service>Private Protocol Authentication Mode), or use the onvif                protocol to add the camera. If it does not work, then Upgrade the video recorder program.

2. The interface prompts error code -18

The reason is that the camera is not initialized, you can initialize the camera and then add it.