Bought the game just after release and I'm struggling with this issue ever since.
When I click on multiplayer button in main menu I'm seeing no one there, like if something was broken. When I tried to create the game myself to play with my friend I couldn't change arena mode at all. If I click on the button, nothing other then arena shows up. The problem is exactly the same on his end too... Also I'm not exactly sure why but every time I get into game multiplayer game creation menu, the button for changing game mode moves from top to bottom and the other way around so I guess that is kinda strange to... 
 I already reinstalled game few times, checked game version, tried test edition... Antivirus is turned off, firewall isn't a problem... nothing seems to fix the issue from the things I mentioned.