I setup an FTP server and tested it by connecting to localhost. For testing if external connections were working; I temporarily disabled my firewall and tried to connect to my computer using my external IP address (whatismyip.com). That didn't work. An online port scanner found the HTTP port open, so I tried to access it through my browser. It was my ISP proxy.

How do I connect to my computer's FTP server from outside the intranet if the ISP proxy is in my way? Assume that I cannot configure the ISP's proxy server.