TP Link w8990 and FTP

[#1]

Had this router up and running from day 0 - with no problems.
It has two usb ports that I can connect a usb disk to - and then access by ftp.
Whilst I can access this over my home network  I can't get this to work for away from home and I'm not sure where the problem lies , router , ip address (for www NOT intranet).
Any ideas people
Thanks

[#2]

You will need to configure the w8990 to allow ftp access from WAN ( for a guide google 'tp link ftp server application guide w8990' ).
Also bear in mind that you IP address can change unless you have a static IP.
You also need to check your PN firewall settings http://www.plus.net/support/security/firewalls/firewallfaq.shtml

[#3]

But don't use ftp - it isn't secure. Try ssh or sftp.