Connectivity Problem with Seven Days To Die - Can't connect to 7DTD and other SteamCMD game server

System Information

Field Value
Operating System Linux - Debian GNU/Linux 12 on x86_64
Product AMP ‘Phobos’ v2.6.2.2 (Mainline)
Virtualization Docker
Application Seven Days To Die
Module GenericModule
Running in Container Yes
Current State Ready

Problem Description

Issue

I cannot connect to any SteamCMD game servers I create.

These are the SteamCMD games I tried running:

  • 7 Days to Die (Error: “Cannot retrieve server info”)
  • Enshrouded (Error: “Server not found”)
  • Valheim (Error: “Failed to connect”)

Meanwhile, I tried creating a Minecraft server (non-SteamCMD game server) and was able to connect just fine.

Some details to note:

  • AMP is freshly installed on a dedicated server.
  • Firewall has been correctly setup and I have confirmed that the required ports are open.
  • Dedicated server is running Ubuntu 24.04.2.
  • For testing, I created two instances of 7DTD, one on a docker container and the other not. Both start correctly but I still couldn’t connect.
  • I also already tried following this guide: Diagnosing Connectivity Issues

Reproduction Steps

  • Created a Seven Days to Die instance
  • Start server
  • Tried to connect to the game server.
  • Fail to connect.
  • Checked and confirmed that firewall settings are correct.