I've configured three different cox accounts for port forwarding and had no problems. Here's what I did to get around issues though.
- Instead of having each device port forwarded (Mumble, VNC, RigPI port 80) I use one port and VPN into my RigPI using OPENVPN
- I used Port 443 since that's a common security port - I forward that Port into my rigPI and then VPN into it, than it's as simple as directing mumble, my browser, and vnc to the core "vpn" IP defined by OPenvpn, it's 10.8.0.1 and I dont' have to worry about custom ports after that
In my personal case - I have a business IP so I can use whatever ports I want.
One friend had a Netgear router so we used a single port on port 443 and that worked fine.
The other friend had a cox router which had Port Forwarding under the advanced settings in the cox wifi app. I also used port 443 to the assigned IP address of the RigPI. No problems.