How to add a camera connected with a 4g router to a hard disk video recorder connected with a network cable?

A camera is added to the hard disk recorder to display the picture. First of all, the camera has established a connection with the router, so there must be a connection between the router and the hard disk video recorder. If the hard disk video recorder is not wireless, you can use a network cable to connect the router lan port with the hard disk video recorder. If the hard disk video recorder is a single network port and other cameras need to be added, a non-network management switch can be added between the router and the hard disk video recorder. That is to say, a local area network connection relationship is established between the camera to be added, the router and the hard disk video recorder, and the ip of the camera and the hard disk video recorder does not conflict, so the hard disk video recorder can be used to manage the cameras in the same network segment. Different brands of equipment access needs to use Onvif protocol, and the same brand access needs to use brand private protocol.