Hi Leemz,
Findports.com says that you also need to open ports 34297 for both TCP & UDP.
Yes, you will also need to open these ports in your Windows Firewall AND in your router. I don't know what version of windows you're using, but this guide will give you the general idea for how to open ports in Windows firewall:
http://www.rfactor-league.com/rFactor/ConfigPorts.htmlI also respectfully recommend that you disable these ports once you're done playing.