I have a NVR system that I need to replace. I have 4 wired IP cameras that are not POE hooded to it via a dumb hub and then a single wire runs to the back of my current NVR. If I get a POE NVR with 8 channels. Can I run a SINGLE Ethernet cord with all four cameras running through it to the NVR for 4 of the 8 cameras? My current cameras use IP addresses.