403 Error on External Connections

I have a Workflow server (2008) that works great when on the internal network. As soon as I move to the Internet and try to connect to it I get a 403 Error. I have an application pool running on the Projects with the proper credentials so I don't know where the breakdown is. I have Port Forwarding enabled on the router and its pointing to port 80 on the Workflow server Default Web Site.

Any ideas?

Thanks!