@DMatt 

There are several parts to connecting a camera using port forwarding.

First you need to assign an IP address to the camera. Pick an IP address that is not being used and assign each the cameras' MAC address to a unique address such as 192.168.0.125. Then reboot the router. The cameras should now be assigned to that IP address. Otherwise, the IP may change on reboot and port forwarding will not work.

Now set up the port forwarding rule using those IP addresses. Different cameras may want you to use specific ports and as I recall, I used 'both' option on my old Foscams which I no longer have. Reboot the router again. 

I then set up a DDNS so I could connect to my cameras from any WIFI in the world which I have. I currently have a Security DVR using port forwarding. I also have Wyze cams which do not require port forwarding. I did not set up the DDNS in the router. I use a different DDNS provider, one from my DVR company. If my ISP IP address changes, I would need to sign on to the DDNS provider to change the ISP IP address. I preferred not to use the ones available on the router.