I tried to play multiplayer but it says, “Player has left” but they did not leave. Here is a youtube video example of this issue: https://www.youtube.com/watch?v=33yd4RUJpD8&t=6s
In order for us to provide better support, we need to see the log generated by Citra. This guide will walk you through how you can obtain the log file: How to Upload the Log File.
Upload a log: How to Upload the Log File and fill in the template that you removed: