Remote Desktop only working on LAN (Server 2008 R2)

I am replacing a Server 2000 machine with a Server 2008 R2 machine. Remote Desktop works fine using the WAN IP on the Server 2000 machine. I have disconnected the Server 2000 machine, and when I try to use Remote Desktop Connection on the Server 2008 machine, I can only access it through the LAN, not the WAN IP.

Do I need to have Routing and Remote Access installed for RDP? I thought that was only need for VPN type connections.

What do I need to do to fix this? I assume it is something simple. Thanks.