For new firmware Hikvision you can enable virtual host.
Configuration > Network > Advanced > Other - tick virtual host and apply
Go to System > Camera Management - click the link under the connect column to have a NAT's connection to the camera.
You can also setup routing now if your are familiar.
Ensure the cameras have their gateway set to 192.168.254.1
Then you can add a route to 192.168.254.0/24 in your router next hop the NVR
If you ping the NVR but can't get the cameras remember to login to the cameras and update the gateway to the NVR.