Some of the pros may chime in with a solution. I'm just an amateur with a suggestion or idea or two
Remotely, you'd have to get into the DVR or NVR with administrative rights to see the camera IPs, I'd guess, depending on the software or hardware used. Or have the cameras individually accessible with a dedicated port through the broadband router. Mine are in a certain order with manual IP addresses and each has its own dedicated port. Party for convenience during setup. Partly because I haven't solved a connection issue yet between the mobile app and the nvr. Having them on an exposed internet port of course poses security risks.