vsftpd problems - failed transfers from remote machines

I recently set up a vsftpd server - connections and transfers work fine from localhost, but I have problems when transferring from a server outside my firewall (i forwarded tcp connections from port 21 to the server)

I can connect to the server fine, but when I try to transfer the following message appears:

227 Entering Passive Mode (192,168,1,20,97,201)
ftp: connect: Network is unreachable

I'm wondering if it's because the ip address 192.168.1.20 - the local ip - is indicated instead of the external ip. Is there some setting I'm missing - in the hosts file perhaps?

I can administer the server with ssh with no problems, but ftp and apache connections are giving me problems.

If anyone has any ideas, they would be greatly appreciated.

Thanks,

-Tim