Is there a solution to the 'unknown host' error of a Minecraft Bedrock server?

I tried to set up my own Minecraft Bedrock server, using the program directly from the Minecraft.net website. Everything runs fine on my computer with Minecraft Microsoft, I can access the server with 'localhost' as the server address as well as my public IP.

My friends, Microsoft & Nintendo Switch, can't access the server, both have the 'unknown host' error. Both tried to get to the server via different ports, I also tried a video where someone changed something in the adapter settings of their internet connection, but this did not solve the problem in my case either. Do you have any ideas?

As far as I know you can only download the server for the Java Edition at Minecraft.net.

There's also a Bedrock version, which is alpha, and can be downloaded for Microsoft and Ubuntu.

Then I have no idea