WEB Dispatcher in different netowrk

Hi Friends,.

Greeting of the day..

We have ECC, Portal and Solman in Intranet  and Web dispatcher in DMZ network. When we connect intranet systems to Webdispatcher, it's not working. please let me know the ECC or Portal or Solman need public internet to communicate Webdispatcher. If not where the configuration should be done. if required public internet which system need for public.

thanks