I did open 2302-2400 ports with DXPortSome users have found that additional ports may need to be opened for multiplayer.
If you still encounter problems with the following open: For client machines the game uses UDP through port 2302. For hosting, you need to allow UDP through port 6073. Also, if you receive a warning from your Firewall saying that
"Remote Machines are attempting to access DirectX" - you will need to allow this to connect properly.
Then you may want to try opening the following in addition: 2302-2400 UDP and 6073 UDP.
now i need to open 6073UDP, how to do it?