I have several Reolink cameras that use port 9000. They do not work via their app unless I VPN in. Is there a way to open up port 9000 so the cameras will work again?
In this case, to be specific, what you want to do is forward ports. And unfortunately you cannot forward the same port to multiple internal IP's at the same time. You have two choices:
You can forward different external ports to your internal camera on port 9000. So 9000 goes to cam1 port 9000, port 9001 goest to cam2 port 9000, port 9002 goes to cam3 port 9000, and so on. You do this in the "Port Forwarding" section on the Firewall rules page.
You can use multiple external IP's to forward port 9000 to multiple cameras. So 1.1.1.1 port 9000 is forwarded to cam1 port 9000, 1.1.1.2 port 9000 is forwarded to cam2 port 9000, and so on. This is done using either 1:1 NAT or 1:Many NAT on the Firewall rules page.