I've just got one of thease mini NVR without much looking into if my ip cameras would work with it. My cameras are 2013 Tenvis IP319W and I don't think they support the RTSP protocol. Not been able to get a feed to the NVR or VLC using a any of the paths I found here
https://www.ispyconnect.com/man.aspx?n=TENVIS
such as
rtsp://IPADDRESS:554/image.mpg etc
rtsp://IPADDRESS:8001/0/av0
rtsp://IPADDRESS:554/LowResolutionVideo
Have I wasted my £25 quid.