Dear RWR community,
you probably already ran through this issue multiple times as well. This might be due to the fact that the game of the HOST has been blocked by the windows firewall or that the HOST most likely sits behind a router and the port he used to host hasn't been forwarded (default: 1234 but you could use whatever port you want).
For informations about how to make a port forwarding please consult the manual of your router.
Here is an general example about how to set up a port forwarding:
http://www.wikihow.com/Set-up-Port-Forw ... n-a-RouterRWR can't detect (yet) if the game listed in "join multiplayer" has the port forwarded or not so please keep in mind to check your settings to have those done before hosting!
Thank you!
Jack