Java APIs

Hi there,

I have written a little client server chat application using RMI.
Running it on my local network ( at university ), chatting is no problem. But once I
change from localhost-area and want to connect via ->Internet<-, I get
"connection refused" error messages in my client. The firewall is turned
off. So what could be the problem? I am using a security policy file ( although actually I might not need one ).
Always get this message ( except in my local network )

Connection refused to host:
XXX.XXX.XXX.XXX. nested exception is. java.net.ConnectException:
Connection Timed out".

I really appreciate help :-).

Thanks,
- Tassilo -