I don't really think that's what needs to be done or is the problem. That would mean your NVR needs another direct LAN connection from the 10.x.x.x NIC to an interface on the router. The router can't magically route to a 10.x.x.x address when it isn't physically connected to that subnet.
Have you tried using the 192.x.x.x IP in place of the 10.x.x.x in the full URL? The point of that "E" icon is to allow you to directly connect to the cameras which are on the NVR subnet while you are on the 192.x.x.x subnet. The NVR is acting like the router in that situation.
My cameras are not on the 192 subnet so what URL should I be using, the NVR? The NVR IP is 192.168.1.254 and when I enter that in, the NVR page comes up as it should, so not sure what you mean by using the 192 address for the cameras?