No need to turn off the NVR. I wouldn't say "port determines IP"... its just a network switch. (ok, managed switch) but still, that doesn't determine anything. The channels are NOT assigned to ports. Any unused channel that is set to "plug and play" could grab onto that new camera regardless of which port it is plugged into. If you want any kind of control over which cameras are assigned to which channels will require you to set the channel to "manual" and then set each camera to a corresponding IP address. If your NVR is full, then your new camera will be assigned to the newly unused channel