Port forwarding not working

Hi guys,

I know this question has been asked to death, but I've tried my best to troubleshoot and nothing seems to work. Been on the phone with Xfinity for over 5 hours and have been passed from one incredibly unhelpful customer support staff to another with no one really understanding what port forwarding is or how it works. Some asked me to just continuously delete and add the same port forwards while others even mistook port forwarding for call forwarding!

I'm trying to set up port forwarding for my Mac Mini. I'm using the default modem / router provided by Xfinity (Technicolor CGM4140COM) and have added a port for it on xfinity.com/myxfi.

Problem is, the port is still closed when I test it by:

1. trying to access the Mac Mini remotely and
2. using open port testing sites such as yougetsignal.com

Things I've already tried:

1. Reset the modem
2. Access gateway settings via 10.0.0.1 (This doesn't work because Xfinity just redirects me to its website and doesn't let me control port forwarding settings: "Managing your home network settings is now easier than ever. Visit xfinity.com/myxfi to set up port forwards, among many other features and settings.")
3. Tried multiple ports (I've ensured that none of these ports are in use or blocked by the mac mini)
4. Deleted and re-created port forwards on myXfi
5. Tried port forwarding on other devices (Two different macbook pros - none of them worked...)
6. Tried port forwarding to both my ethernet and wifi IP addresses (neither worked)

If anyone from Comcast sees this @ComcastBrittany @ComcastJessie , would appreciate the help!