Multiplayer joining session error

Alright, so i followed a tutorial on YT to make my game multiplayer. Then, as i went forward with the tutorial, i changed the level i wanted the client to join when the “Connect” button is pressed. All because this is a main menu. When i pressed the “Connect” button though, it gave an error. (The client can join a host with the host’s IPv4 address.)

But when i changed the level to join when i pressed the “Connect” button to the existing level, it seemed to be working fine.

Here are the nodes :