Port Forwarding With Router

[pobri19]

Hi, so this is my problem. I'm trying to get a reverse proxy program working (so that I make the reverse proxy server, and when a friend executes that server it connects to my machine and to the reverse proxy client) but I'm having troubles with the port forwarding. Basically this is my setup:

2 Local Computers > D-Link Ethernet Router > ADSL VOIP Modem (plugged into the WAN port of the router) > Phone Socket

If I connect my two computers directly to my modem, and take the router out of the equation, and forward the port on the modem, the reverse proxy server can connect to my client, and canyouseeme sees the port (port 19999) as open...

But if I have my computer plugged into the router, and forward the port on the router AND the modem, canyouseeme sees the port as closed and the server doesn't connect to my computer... Could someone please explain to me how I'm supposed to port forward if I have a router in the equation (do I need to forward it on the router AND the modem, just the modem, or just the router, and why?)

The IP address of my modem is 192.168.1.1
Subnet mask: 255.255.255.0

The ip address of the router is 192.168.0.1
Subnet mask: 255.255.255.0
DHCP server enabled

My computers IP address: 192.168.0.2
My computers default gateway: 192.168.0.1
DNS: 192.168.0.1
DHCP: 192.168.0.1

Does it matter that they're on different IP ranges?
Is it possible to set it up so that my router is using the same range as the modem, and still get internet connectivity? I tried... but I couldn't figure out how to get it to work. It wouldn't let me access the internet.

I think that's everything... Any help would be GREAT! Thanks a lot guys!