Xfinity Cisco port forwarding nightmare

I'm having a nightmare setting up the port forwarding for Rust using my Cisco DPC3941T with Xfinity.
I've done this before, but only on Airport Extreme which is infinitely more intuitive.
I'm not sure if its because I'm running ethernet for the first time, not sure if what I'm doing wrong is in my batch file:

RustDedicated.exe -batchmode -hostname "WHYWONTYOUWORKONLINE" -port 28015

It works fine for me, I'd just like to have my friends play with me.

 

From my experience of teamviewing people and helping them with Portforwarding. Having an Ethernet connection seems to be the usual problem, including the possibility of some configuration that don't work well with Portforwarding.

 

I have completely port forwarded my rust server, plugins work, but whenever I give my friends my public ip address to join, it says that the login failed. I am not using Ethernet, but am having a nightmare as well. anything I should try?