Switch from Active mode to Passive mode.
Globally via Options > Preferneces > Proxy Tab > Use Passive Mode
Per site via Site Manager > Options Tab > Use Passive Mode
If you require Active Mode you'll need to configure your router to forward the ports to your computer and enter your external ip in FlashFXP. Take a look at
http://forum.flashfxp.com/showthread...&threadid=1110 or try searching the forums for others