That will work if you connect the PC to an unused NVR PoE port. What's required once you have identified the camera IP addresses is to match them with the IP addresses that are configured on the NVR PoE channels they are connected to. You could change either the NVR channel setting, or the camera IP address. But there is a potential problem, if the cameras were added with the NVR PoE channels in 'Plug&Play' mode. The NVR may have used it's own password to set up the cameras. If not, and you assigned it yourself - you are going to be OK. If the NVR set the password - there is a way to extract the password from the cameras if the firmware is older than 5.4.5 But let's see how you get on first.