Connectivity Problem with Minecraft Bedrock - Malformed response from server

Technical Support
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System Information

Field Value
Operating System Linux - Debian GNU/Linux 13 on x86_64 (this is UNRaid)
Product AMP ‘Proteus’ v2.8.0.4 (Mainline)
Virtualization None
Application Minecraft Bedrock
Module GenericModule
Running in Container No
Current State Ready

Problem Description

Issue

Diagnostics copy pasted from AMP GUI

OS Linux
Platform Debian GNU/Linux 13
System Type x86_64
Hardware Platform Notebook P17SM
CPU Model Intel(R) Core™ i7-4800MQ CPU @ 2.70GHz
CPU Layout 1S/4C/8T
Installed RAM 15928
Virtualization None
Network Mode Standard
Module ADSModule
Module Application Application Deployment
Loaded Plugins FileManagerPlugin, EmailSenderPlugin, WebRequestPlugin, WebhookPlugin, LocalFileBackupPlugin, CommonCorePlugin, AnalyticsPlugin, StorePlugin
Application Name AMP
Application Version 2.8.0.4
Codename Proteus
Tools Version 2.7.2
Release Stream Mainline
Build Spec Release
Build Date 24/07/2026 17:13
InstanceID a11c771e-93fd-4843-b76f-6394a073f3d9
Last Executable /usr/bin/tmux
Last Arguments -f /dev/null new-session -s “AMP_rockyminecraft01” -d "cd ‘/home/amp/.ampdata/instances/rockyminecraft01’; /home/amp/.ampdata/instances/rockyminecraft01/AMP_Linux_x86_64 +Core.Webserver.Port “8082” +Core.Webserver.IPBinding “127.0.0.1” +Core.AMP.InstanceID “–--” +Core.Security.MetricsHMAKKey “**********”
Last Process ID 2552

Problem Description

Issue

A Bedrock Dedicated Server instance that was working correctly a few months ago has stopped being reachable by any Minecraft Bedrock client, with no configuration changes made on my end. This affects both a fresh instance created to rule out per-instance config issues and the original instance — same result on both.

Symptom on the client side: the server never appears via LAN auto-discovery, and adding it manually by IP results in an infinite “Loading ping” with no MOTD, player count, or version ever displayed. This happens identically on multiple client devices (PC and mobile), on the same LAN as the host and from outside the network.

Reproduction Steps

  1. Start the Bedrock instance in AMP — it reports “Running”, and the console log shows a clean startup ending in “Server started.” with no errors (full log available on request).
  2. Attempt to connect via the Minecraft Bedrock client, either through LAN auto-discovery or by manually adding the server via IP:port.
  3. Client shows infinite “Loading ping” and never receives server details.
  4. Attempting to connect anyway just times out.

Diagnostic Steps Already Completed

I want to flag upfront that this has already been narrowed down well past general network troubleshooting, so I’d appreciate skipping straight to a technical response rather than first-line steps like restarting the router/server, which have already been done multiple times with no change:

  • Docker port publishing confirmed correct: ss -tulpn on the host confirms docker-proxy is bound and listening on the correct UDP port on both IPv4 and IPv6.
  • Router/DDNS confirmed correct: Port-forward rule verified as UDP-only to the correct current internal IP; DuckDNS hostname confirmed to resolve to the exact current public IP (verified via curl ifconfig.me matching nslookup); also tested with the host placed in the router’s DMZ, with identical results.
  • Host firewall confirmed not blocking: iptables -S shows default ACCEPT policy on both INPUT and FORWARD chains; no rules reference the port; no VPN/firewall containers present on the host.
  • Packet-level capture confirmed correct routing inside the host: tcpdump shows an incoming client ping correctly reaching the container via the docker0/veth bridge, and a reply being generated and sent back out the physical NIC addressed to the correct client IP and correct (verified, non-stale) destination MAC address.
  • The actual reply payload is malformed. Sending a manually constructed RakNet Unconnected Ping (0x01 + timestamp + magic + client GUID, 33 bytes total) to the server directly and inspecting the raw response bytes shows the server replies with a syntactically valid Unconnected Pong header (0x1C + timestamp + server GUID + magic, 33 bytes) but is missing the trailing server-info string entirely — there isn’t even a 2-byte length-prefix for it, let alone the MOTD/version/player-count string a valid Bedrock Pong requires. This is why clients hang indefinitely: they receive a reply but can’t parse a server listing out of it.

Raw reply bytes captured for reference:

1c 00 00 00 00 00 00 00 00 8a 5e d8 5d 94 fa a1 80 00 ff ff 00 fe fe fe fe fd fd fd fd 12 34 56 78

This points to the issue being in how the Bedrock server/AMP is generating its status reply, not in networking, Docker, or firewall configuration, all of which have been individually verified working above.

Additional Notes

I found a couple of other reports that may be related, in case useful for cross-referencing: “Connectivity Problem with Minecraft Bedrock - No servers can be found after updating” and “Connectivity Problem with Minecraft Bedrock - Bedrock Edition couldn’t find AMP server” on this support forum, both describing the same “was working, then broke with no config changes, clients can’t find the server” pattern.

I’ve already tried checking for AMP updates and reinstalling/redownloading the Bedrock server binary through the instance.

Happy to run further diagnostics — I’d just appreciate this being routed to someone who can look at the actual status-response generation rather than general connectivity troubleshooting, since that side has been thoroughly ruled out. Thanks in advance for your help.

Reproduction Steps

  • rebooted everything
  • tried connecting from multiple clients
  • updated everything and tried a new executable for the game