| Error Message You See | What It Actually Means | The Fix | | :--- | :--- | :--- | | "UPD Connection Failed" | UDP port 27015 is blocked by Windows or router. | Run the "Allow UDP" script in Part 3, Step 2. | | "Host Migration in Progress" | Steam Relay lost connection to Relic. | Host must disable "Steam Networking" in Steam settings. | | "Version Mismatch (LAN UPD)" | One PC has a different CoH2.sga archive. | Verify integrity of game files on all PCs simultaneously. | | "Cannot find session" | Windows Network Discovery is off. | Turn on "Function Discovery Resource Publication" service on all PCs. |
On every PC (Host & Clients):
– The CoH2 Vet.