Arris TG1682 I cant seem to access forwarded ports...

I have an Arris TG1682 Cable Modem
I am trying to access my Camera System when I am away from home
I have forwarded the Ports from my camera system, but when I try to see them I get an error/Timeout message

I have tried to use https://portchecker.co/check
and no matter what port I put in, its tells me the port is closed

How do I open up the modem to allow me to access ports from the outside world

Cox tech support from calling in is totally worthless on this subject