Troubleshooting FTP

Hi All

I have a client that needs to be able to send data from their AS400/iSeries
to my iSeries using FTP and have been in the process of trying to set up my
end which I believe is working.

I have a PC based FTP server which is listening on port 21 and have set up
port redirection to accept requests on, say, port 400 and redirect those
through to port 21 on the iSeries.  From within my firewall if I FTP to my
domain's URL on port 21 I get the PC based FTP server, whilst if I FTP to
port 400 I get the iSeries.  If I dial in to a third party ISP and FTP in to
ports 21 and 400 I get the same results.  From my iSeries I can also FTP to
port 400 of my domain's URL and loopback into the iSeries.

My client, however, is unable to connect to the iSeries although he can get
through from his box to the PC based server on port 21.  He's running v5r3
and I'm on v5r1, but whenever he tries to connect to port 400 it just seems
to hang.  He believes that as he can get through to port 21 then his box is
set up correctly and it must be at my end that the connection isn't
happening.

Has anybody got any ideas as to what we can check on both systems to make
sure that everything is working as expected, or if there is anywhere I can
check on my box to see if a connection is being made.  Nothing appears in
the QSYSOPR message queue or any of the QSYSWRK subsystem jobs that I can
see.

Thanks

Jonathan