Hi,
You should be able to address the IP cameras using the IP address of the NVR with a port number.
Assuming you NVR is 192.168.0.20 then you can get to the cameras using
192.168.0.20:65001 ie add a different port number to the NVR to access each of the the camera.
If in the NVR you goto configuration and camera management you will see the port number used for each camera.
Shout if you have problems.
Cheers David