Connectivity Problem with Minecraft - My friends from tlauncher can't join the server

System Information

Field Value
Operating System Linux - Debian GNU/Linux 12 on x86_64
Product AMP ‘Callisto’ v2.5.1.6 (Mainline)
Virtualization Docker
Application Minecraft
Module MinecraftModule
Running in Container Yes
Current State Sleeping

Problem Description

Issue

I basically bought this server for playing with my friends.
They are using tlauncher and they can’t join.
The error code is “failed to verify username” and i don’t know how to fix it.
Can you help?

Reproduction Steps

  • I looked in the Console if there was an option
  • I didn’t find anything and i looked on youtube
  • i disabled onlinee mode in the server proprieties