following the posts i think you can use this information:
this is what you should try at you home-network
on windows use the command: ipconfig / all
on linux: ifconfig and route
to view your nework configuration. There must be some entry called gateway or defaultgateway . This is the device connecting you to the internet.
once you got the gateway address, try connecting to it via InternetExploere/Mozillal in the form
http://192.168.0.254 ( replacing 192.168.0.254 with your gateway-address )
you should know the username / password of the device ... if not , locate the device physicaly ( with your hands
) .. and look which device it is .... then ask google for: "mydevice default password".....
to reach your ftp-server, which ( i assume ) is somewhere in your lan, you have to open at least port 21 on this gateway-device. In it's menu there might be some entry like "Port forwardings" .... there you tell it to forward all traffic on port 21 to the (private) ip-address of your server ( ifconfig)
also a nike site for checking if your ports are open:
www.grc.com , then click shieldsUP , scroll down to hotspots, and klick shieldsup agin.
then you see you official internet IP and can also to a portscan to see if the port 21 is open.
hope it helps
cu