Help changing net mode at runtime

Hey there so im making an main menu for my multiplayer game and it needs to be ran in standalone mode. Everything works inside the Mainmenu level and it looks great. I have setup steam advanced session servers but after im ready to open the new map i lOpen level by name and it opens it. I use the option ?listen and absolute is set to true but i dont think it changes from play as standalone netmode to Play as client netmode and the mecanics only works for the player that made the server. how can i change the netmode at runtime basically?