Can't host a server with steam

Hi! I’m having a problem with steam servers. I can’t host any sessions through steam but without it I can. So what it does is when I press host button from my main menu it opens the level for a second and then throws me back to the main menu. If you’re wondering I’m using advanced session plugin. I put an error message from on failure of the Create Session Advanced node and it always gives that error when I try to host. I’m clueless and I have no idea how to fix this.