Issue with Hosting a Game Using Steam Online Subsystem in Unreal Engine 5.4

Development Programming & Scripting
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I’m encountering an issue with my multiplayer game on Steam, and I could use some help troubleshooting.

Setup

  • Game: Multiplayer game developed in Unreal Engine using Advanced Sessions and Steam Subsystem.
  • Server: Host server is created using the Create Advanced Session node in the Game Instance.
  • Client: Connects to the hosted server via Find Sessions and joins successfully.
  • Steam Overlay: Fully functional, launching the game via Steam displays the overlay with no issues.
  • Deployment: Game is uploaded as a valid Steam depot.

Issue

When connecting to the hosted server, the ping always shows as 9999, even when using two different Steam accounts on separate computers on the same local network. This issue also causes erratic physics behavior, such as players being stuck or moving too fast.

Logs

Below are two key logs:

1. Log from Steam when launching the game:

Setting breakpad minidump AppID = 1234567
SteamInternal_SetMinidumpSteamID:  Caching Steam ID:  76561198123456789 [API loaded no]

2. Log from the standalone session:

LogSteamShared: Display: Loading Steam SDK 1.57
LogSteamShared: Steam SDK Loaded!
LogOnline: STEAM: Starting SteamWorks. Client [1] Server [1]
LogOnline: STEAM: [AppId: 1234567] Client API initialized 1
LogOnline: STEAM: [AppId: 1234567] Game Server API initialized 1
LogOnline: STEAM: Initializing SteamNetworking Layer
LogOnline: OSS: Created online subsystem instance for: Steam
LogOnline: OSS: TryLoadSubsystemAndSetDefault: Loaded subsystem for type [Steam]
LogOnline: STEAM: Missing P2PCleanupTimeout key in OnlineSubsystemSteam of DefaultEngine.ini, using default

What I’ve Tried

  1. AppID: Verified the AppID in the game files, Steamworks settings, and DefaultEngine.ini.
  2. Standalone Tests: Ran the standalone game with -log and confirmed SteamSubsystem initialization messages.
  3. Steam Overlay: Verified that the overlay is working correctly.
  4. Server and Client Tests: Hosted and joined a session using two accounts on different PCs but on the same network.

Despite the above, the ping remains 9999, which seems to cause instability during gameplay.

Questions

  1. Could this be an issue with how SteamSubsystem handles local connections, or is it related to networking configuration in Unreal Engine?
  2. Is the log message [API loaded no] indicative of a problem with Steam API initialization, despite the subsystem seemingly working?

I’d appreciate any insights or suggestions for resolving this issue. Thank you!