I don't know what's going on as of recently in this beta-testing because I haven't been able to play much but I was able to access the multiplayer as some point over the last week. But as of lately, I haven't been able to.

I'd go to multiplayer, hit "join game", and it'd say "no sessions were found". So then I'd try "host game", and then it'd say that I "failed to host the game".

The single player runs perfectly fine at max settings and everything so I'm not sure what it may be related to.

Maybe check your firewall to ensure the game is still allowed access to the net.