Fixing Host Migration Failed in Meccha Chameleon

In peer-to-peer (P2P) multiplayer games like Meccha Chameleon, the host’s machine acts as the dedicated server. When the host disconnects, leaves the lobby, or experiences a crash, the game attempts a process called Host Migration to transfer server authority to another player without disconnecting the session.

If you receive a “Host Migration Failed” error or are kicked back to the main menu with a “Lobby Disconnected” warning, the transition has failed. This is typically caused by NAT type conflicts, closed router ports, or version mismatches during the transition.

Follow this troubleshooting guide to resolve host migration failures.

P2P Network Topology and Host Selection

Understanding how the game handles host transition helps diagnose where the network handshake fails.

                      P2P LOBBY MIGRATION ROUTE
                      
        [Original Host PC]  === (Leaves/Crashes) ===>  Match Pauses
               ||
        [EOS Matchmaking]   ---> Evaluates remaining players
               ||
        [Evaluates Ping]    ---> Picks lowest latency client
               ||
        [NAT Handshake]     ---> Initiates direct UDP connection
               ||
   +-----------+-----------+
   |                       |
(Open NAT Joiner)     (Strict NAT Joiner)
   |                       |
[Migration Successful]  [Migration Failed / Disconnect]

• Open NAT Candidate: The game selects a player with an Open NAT and low ping. Handshake completes instantly.
• Strict NAT Candidate: If all remaining players have a Strict NAT, they cannot receive incoming connection requests from other players, causing the migration handshake to fail.

Host Migration Troubleshooting Decision Tree

Follow this tree to resolve lobby disconnection issues:

                     [Host Migration Failed]
                                |
                     Evaluate NAT Profiles
                   Are players using Strict NAT?
                   /                            \
                (Yes)                           (No)
                 /                                \
     [Configure Router UPnP]            Check Match Latency (Ping)
     [Set Port Forwarding rules]         Are players experiencing lag spikes?
                                         /                       \
                                      (Yes)                      (No)
                                       /                           \
                             [Fix Lag Spikes Mid-Match]     Verify Map Cache Status
                                                            [Check Custom Map Loading]

• Branch A: NAT Block: Strict NAT profiles prevent players from hosting or receiving P2P handshakes. Jump to NAT Configuration Fixes.
• Branch B: Lag Spike Disconnect: Heavy packet loss causes the game to timeout during host migration. Jump to Network Latency Fixes.
• Branch C: Custom Map Cache Mismatch: The new host cannot load the map, stalling the lobby. Jump to Map Integrity Verification.

Detailed Step-by-Step Fixes

1. Explicit Windows Defender Firewall Exclusion

Sometimes, even if Windows reports that the game has access, security policies block incoming UDP connection requests on secondary ports required for peer migration.

1. Press the Start Menu, type Windows Defender Firewall with Advanced Security and open the app.
2. Click Inbound Rules in the left sidebar.
3. Click New Rule… in the right Actions sidebar.
4. Choose Program and click Next.
5. Browse to the exact location of the game shipping executable: Steam\steamapps\common\MecchaChameleon\Binaries\Win64\MecchaChameleon-Win64-Shipping.exe
6. Select Allow the connection.
7. Check all three profiles: Domain, Private, and Public.
8. Name the rule Meccha Chameleon P2P Inbound and save.
9. Repeat the steps under Outbound Rules creating an outbound exception for the same file.

2. Configure Router UPnP and NAT Settings (NAT Configuration Fixes)

For P2P host migration to succeed, at least one of the remaining players must have a network layout that allows inbound connections.

1. Log into your router’s administrative control panel (typically 192.168.1.1 or 192.168.0.1 in your web browser).
2. Locate the UPnP (Universal Plug and Play) setting (usually under Advanced, Gaming, or WAN options).
3. Toggle UPnP to ON. This allows the game to automatically open the required ports when it needs to take over hosting duties.
4. For detailed step-by-step instructions on improving your NAT profile, see our NAT Type Fix Guide and Stuck on Connecting Fix Guide.

3. Configure Manual Port Forwarding Rules

If UPnP is disabled or blocked by your router’s security policies, you must manually forward the ports required for hosting.

1. In your router settings, navigate to the Port Forwarding section.
2. Add a new rule to forward the following ports to your local PC’s IP address:
   • UDP Port Range: 27015 to 27030 (Steam P2P Voice and Matchmaking)
   • UDP Ports: 3478, 4379, 4380 (Epic Online Services queries)
3. Save the changes and restart your router.

4. Verify Custom Map Cache Status

If a host migration occurs on a custom Workshop map, the newly selected host must have the map fully cached. If the map fails to load, the migration fails.

1. If you are playing on custom maps, make sure your files are verified. Read the Workshop Map Won’t Load Guide to check file status.
2. Ensure background downloads are paused during match transitions. High network utilization during load screens can trigger a connection timeout.

5. Limit Packet Loss and Lag Spikes

Heavy packet loss during matches will cause the matchmaking registry to lose connection to your client, triggering an accidental host migration.

1. Use a wired Ethernet connection instead of Wi-Fi for hosting.
2. If you experience mid-match freezes before disconnections, follow the steps in the Lag Spikes Mid-Match Guide.