FTP Port Forwarding

Hi, I have an ftp server running on my computer, I have given it a random port number and I am able to connect to it on my home network as I would expect. I tried then to port forward this FTP server via the xfinity app and the whole setup of port forwarding (please don't recommend me the link that refers to the steps on port forwarding), I entered the specific port (not a range) of my ftp and also chose the device the FTP was on. I chose TCP only and that's all the options it gave me I think. But it didn't work when I went to another house and tried it on a different Wifi, is there a step I did wrong? Or something else? (Also I do have a static IP on my computer so that shouldnt be an issue i think)