Bug/Issue Connection failed! can't join multiplayer.

So we both have the game on steam, and we both tried hosting the game, but we keep getting "connecting" then "connection failed" after a while.
This is my first time playing multiplayer, but she said she already played multiplayer with her sister before and it worked.
any help would be appreciated

 

I have the exact same problem. I have tried on 2 different PCs and on 2 different accounts and the only thing that I believe can be the problem is something with my internet. I play with satellite which is based off a SIM card. I also tried my phone's hotspot and both of those prevented me from playing any multiplayer (connecting to others and having others connecting to me). Hopefully this will be fixed, but I've had this problem since the Beta and I haven't seen one functional fix yet.

 

I know for a fact that the game should work when playing off a phone's hotspot, as I've done it with mine before (4g LTE Verizon). The game seems to be really picky with connection strength and ping. I was having the exact same problem trying to play over WiFi with my girlfriend on the same network and it just did not want to work. (She was wired, I was on WiFi) so eventually I got desperate and tried my phone hotspot and it worked. I don't have unlimited data so obviously I wanted to find a different, better solution so eventually I just decided to run a 100ft Ethernet cable all the way to the router and it worked flawlessly. We've played for hours on end without problems. I'm using a FiOS ISP.