I've finally discovered where XFinity has buried the port forwarding.
Note: their documentation has not been updated. it says to go to
But it is really under gateway--scroll beneath all connected devices--Select "More".
I did this because my forwarding to 3389 to my home PC from the outside world has stopped working. I have a replacement router coming, but just to test I deleted the port forward and added one for 3390. I can ping the external IP of my router from the outside, but not connect to 3390, or 3389 as I've put it back to.
This is ridiculous. Port forwarding has to be one of the most basic networking tasks for any home network and XFinity has no idea how to repair. I am hoping my new router fixes things, but has anyone else had similar issues with their XFinity home network? I'm about ready to buy my own router and stop renting this POS.