Answer:

Cause 1: No available channels can be distributed to the new camera. 

Solution: If all channels have been assigned to cameras, and you are adding a new camera, in this case, you have to remove the cameras which are no longer in use and then manually distribute a channel to the new camera, as each camera requires a channel distribution. 

Cause 2: The new camera has been distributed with the same IP address as the previously added cameras. 

Solution: Delete the old IP address from that channel, and click Search to find the new IP address for the new camera, then assign this IP address to the channel and the new camera.

(In the above image, it shows all four cameras have been assigned with a channel and an IP address. You can’t add a fifth camera. If you are replacing one of the cameras, make sure to delete the IP address for that camera FIRST, and then search new IP address for the new camera before you add it to the channel.)

Cause 3: It shows "offline"/ "connection failed" on the IP channel page.

Solution: In this case, please reboot both the NVR and the camera. Then, check whether the camera is powered on by the NVR: Cover the daylight sensor, or place the camera in a dark environment. After a few seconds, if the IR LED turn on, or some sounds can be heard, it means the camera is powered on.

Also, please check whether the camera's corresponding PoE port lights. If the light is not on, please change into another working cable and another working port.