You will need a port forwarding rule on each router for the nvr port (usually 8000 on hikvision). Port forward the nvr port from the Internet wan to the inner router wan address (use static ip) the port forward from wan to the nvr on the camera network router.

Hikvision Network Configuration Help

I have a question. I'm running a Hikvision 16 channel NVR with 14 cameras. All IP cams have been trimmed down to low video quality @15 FPS. Because of all the network traffic, I had to put the NVR and cameras on the same segment, using another router 192.168.10.X strictly for the cams and NVR, then running that router into the router that connects to the internet at 192.168.1.X. I need to figure out how to get the NVR through both routers so remote access can be used again. Any ideas?