Dear All Experts

I have a little problem in connecting 1 computer behind monowall to outside
world for our convenience of working.

Basically I have this server that holds our file, I wanted to create
somekind of VPN connection to our internal server that passes through the
ADSL modem so that we can connect to our office from anywhere.

Here is the current diagram of our network:
								     |--
Network PC1
Internet -- DSL Modem (Prolink 9000H) -- Monowall ---|-- Network PC2
		(11.121.1.1)				     |-- Server

Now the plan is that I want to connect the server via internet. I manage to
make my modem open and I have a static ip address on the modem site (ex:
11.121.1.1). But when I call the IP from the internet, it only goes as far
as the modem interface. Although, I think I set the modem to check if I
required port 80000, it should direct to the Monowall, then I am blank on
what needs to be done.

I was wondering if anyone expert with such modem or case? Or can anyone give
me the big picture or the basic on how to connect such case?

Any help would really be a great help.

Thanks
Rendra