FTP File Problems

Hello Xfinity.

I am having trouble connecting to an FTP server via FileZilla, using Port 21. I've tried to use port forwarding to make sure my desktop allows forwarding through, but this didn't work. The weirdest thing is that, I can connect to the FTP server via my iPhone personal hotspot, but not the main Xfinity network. I've also tried to see if there was anything in the default gateway settings but nothing showed up.

What would be the best solution to this? Is there something wrong? I need help on this. Thanks!