Having Problems with Multiplayer

[Denari]

I'm not sure if this is the right category for this but eh.

(Playing through Steam, I'm hosting)
My friend and I played the game perfectly fine up until the first boss, when he got disconnected. We tried restarting and it worked for about five minutes. When we tried again (both of us tried hosting), the screen got covered with a gray vignette, which disappears after a few seconds then goes back to normal. We tried using Hamachi and I port forwarded, but they didn't work. We've try every once in a while and it occasionally works, but only for a short period of time.

Thanks in advance

 

[Own]

When it does that little gray fade thing, just have the person trying to join close and restart the game. Works for me.