Connectivity Problem with Application Deployment - Players cannot connect – “Connection refused: getsockopt”

System Information

Field Value
Operating System Linux - Debian GNU/Linux 12 on x86_64
Product AMP ‘Phobos’ v2.6.3.2 (Mainline)
Virtualization QEMU_KVM
Application Application Deployment
Module ADSModule
Running in Container No
Current State Indeterminate

Problem Description

Issue

My Fabric 1.21.1 Minecraft server ) is running and marked as “Listening” on both SFTP and Game ports, but no external connections can be made. The console confirms the server is active and bound to the port, yet all players receive “Connection refused: getsockopt.”

Reproduction Steps

  • Started the Fabric 1.21.1 Minecraft server in AMP.
  • Server console shows “Done! For help, type ‘help’” and the port is listening.
  • Tried connecting using server ip address from Minecraft client.
  • Received “Connection refused: getsockopt.”