Authentication problem - Routing and Remote access

I have a domain controller(windows 2003 server) that run's IIS with
several sites. All have been working fine until I switched from ICS to
Routing and Remote Access. After I have installed Routing and Remote
access the sites that does not allow anynomous access stoped working.
When I try to surf to an site that requires authentication I never get
the login box on the client it only waits and after a while I get a DNS
error(there is no problem with the DNS). I only have the problem with
the external network adapter if I try to reach the site on the internal
adapter everything works fine. I get the login box and will be abel to
login.