Thanks! I was hoping that was the answer.
I wasn't sure if the NVR's were more sensitive to issues if cameras were plugged directly into the POE on the NVR as the traffic from the user has to route via the NVR DNS which in turn could affect some of the cpu power and bandwidth (when they access the camera).
So far the only issues Ive seen (when connected to the NVR POE port) are where the virtual network tickbox has deactivated itself after several hours (on the K series), but that seems to have been fixed earlier this year.
My theory has always been to let the cameras do the optics, compression, detecting and alerting, then let the NVR just record the data to the HD, user playback and notifications. ...maybe I'm overthinking it as the hikvision software on the K series can be quite flakey and it feels like the hardware is a bit underpowered for 4 x 8MP cameras. ...hence why I was questioning if using the NVR POE had any drawbacks as maybe its an option to ease the pressure off the NVR by plugging everything into a 16 port POE switch so we connect to the camera directly.