Anger Wrote:firstly i would get myself a static ip address (assuming you don't already) i use dyndns.org. next see if your router/modem supports dyndns updating, so that when your ip changes it will automatically correct it. that makes sure your ip address is correct. next make sure your allowing complete access to the ftp through whatever firewall your using - remember there will be more than 1 port will need to be forwarded, and don't forget forwarding in the router/modem. next check local access to the ftp (assuming the server is running on the same machine your testing from - ftp://127.0.0.1:port/path/) if this step fails then they can't see it because somethings preventing it from working.
i would allow a limited any user account till you get it working then you can make it work for a single person - i had to do this initially because setting up a single user account wasn't as easy as it should have been. i can't remember if theres anything else you can try but i will try and help some more if needed. good luck.