it depends on your router though, but here's a quick guide:
-go to
http://portforward.com at the bottom of this site, you'll see your IP adress.
-Copy paste your IP adres in the text bar of internet explorer and hit enter.
Doing so will bring you into your router.
-When you're in your router menu, check for something that sounds "port forwarding" or "open/close ports" or whatever (this varies from router to router, there are guides on the site for specific routers if you don't know what to do).
usually it's located under the Firewall category.
-When you're in the port list, add the port that is shown under your login details when you're in the Sacred 2 multiplayer lobby. (under your login and password the game shows you your Sacred IP and port, write down that port nuber)
for example, my Sacred 2 port is 6800, i just added 6800 to the port list and clicked "save settings", it works to host for me now.
note that it's important to forward the port that Sacred 2 gives you. If you create a game it always says port 7011. If that isn't your designated port, change it to the one it says under your login information (being the one you forwarded of course)