Problem sending files to external connection

Hello there

i have problem in sending file/s.

my setup of openfire is like this:

I have server which is i installed openfire

i have workstation which i installed PANDION as my client messenger

On my server i used two LAN card

eth0: = I used external IP 2xx.xx.xx.xx

eth1: = I used lnternal IP

all my workstation in the same place i let them used the internal IP

but all workstation in other country for example taiwan i let them to used external IP address and also a PANDION as they client messenger

when everybody are onlined we can send text info each other but once the client used internal IP and send one file to external, i got an error message failed

but if i communicate internal IP to internal IP i have no problem…

I attached file for additional detail on my server setup

please help…

thank you…