If the NVR has been connected to four cameras it won't auto-connect any new camera. 

In case you need to replace a camera with a new you need to follow the steps below via the interface of the TV.

1. Disconnect the camera you want to remove. 

2. Connect the new camera.

3. Right click to see the menu bar. Choose the camera symbol. The new camera is found but disconnected by default.

4. Choose a channel that is available. In this case channel 2.

5. Select Apply. The NVR will connect to the new camera.