Since around 1:00 am on October 5th, my friends have been unable to enter the world I created.
Up until then, I had been able to play without any problems, but suddenly the message "You can no longer participate in this world" was displayed, and I tried restarting and re-downloading many times, but I still can't enter. I'm here.
Also, after a few days of communicating with my friends, I was no longer able to enter the "world created by my friends." At that time, the message "Unable to connect, please restart the client" shown in the attached image will be displayed.

My friend and I have subscribed to Nintendo Switch Online, and we have confirmed that we can play other games online.
I have also tried the following methods, but there is no improvement.
・Restart the main unit (Switch)
・Re-download the software
・Re-registration of friends
・Play at different times

I don't know how to solve this problem, so please help me out.

I'm translating from Japanese, so I'm sorry if the text is difficult to read.