The camera should meet two requirements.
1. It must support the onvif protocol.
2. The IP camera's resolution should be equal to or lower than resolution NVR. For example, if the NVR is 720P but the IP camera is a 1080P resolution, NVR is not able to display video of this IP camera.
Below is instruction.
1. Plug camera to router by cable and connect the camera to a power source by adapter.
2. Connect NVR to the same router by network cable.
3. Go to the main menu---system---digital-digital channels to tick enable and click Add.
4. It will search for the camera's IP. Double click IP to add it.
Come back to the main screen and image of IP camera appears.