This isn't entirely about static port-forwarding. As others have pointed out, STUN, VoIP, PASV, etc rely on deterministic NAT behavior to work. That is not alwa

This isn't entirely about static port-forwarding. As others have pointed out, STUN, VoIP, PASV, etc rely on deterministic NAT behavior to work. That is not always guaranteed, and often out of your control.