Hey,
we are currently porting a 10 year old UE4 game to UE5.7 for a remaster effort. The code was unchanged for nearly 10 years and the Steam Multiplayer worked in the old version.
In the UE5 build we can host servers and other players can see the entries in the Serverbrowser. However once we join we get this error:
[2026.07.21-14.05.18:782][634]LogOnlineSession: STEAM: Using P2P Data for Connection Serialization
[2026.07.21-14.05.18:782][634]LogOnlineSession: OSS: Join session: traveling to steam.76561198034659609:7777
[2026.07.21-14.05.18:782][635]LogGameMode: Display: Match State Changed from InProgress to LeavingMap
[2026.07.21-14.05.18:782][635]LogGameState: Match State Changed from InProgress to LeavingMap
[2026.07.21-14.05.18:782][635]LogGlobalStatus: UEngine::Browse Started Browse: "steam.76561198034659609/Game/System/Maps/MainMenu"
[2026.07.21-14.05.18:782][635]LogNet: Browse: steam.76561198034659609/Game/System/Maps/MainMenu
[2026.07.21-14.05.18:812][635]LogNet: InitBase PendingNetDriver (NetDriverDefinition GameNetDriver) using replication model Generic
[2026.07.21-14.05.18:812][635]LogInit: WinSock: Socket queue. Rx: 32768 (config 32768) Tx: 32768 (config 32768)
[2026.07.21-14.05.18:812][635]LogNet: Created socket for bind address: 0.0.0.0:0
[2026.07.21-14.05.18:812][635]LogNet: IpConnection_2147482263 setting maximum channels to: 32767
[2026.07.21-14.05.18:812][635]PacketHandlerLog: Loaded PacketHandler component: Engine.EngineHandlerComponentFactory (StatelessConnectHandlerComponent)
[2026.07.21-14.05.18:813][635]LogHandshake: Stateless Handshake: NetDriverDefinition 'GameNetDriver' CachedClientID: 5
[2026.07.21-14.05.18:813][635]LogNet: Game client on port 7777, rate 100000
[2026.07.21-14.05.18:813][635]LogNetVersion: StrikeForce 2.0.0, NetCL: 0, EngineNetworkVersion: 43, GameNetworkVersion: 0 (Checksum: 531097437)
[2026.07.21-14.05.18:813][635]LogSockets: Warning: GetAddressInfo failed to resolve host with error SE_HOST_NOT_FOUND [11001]
[2026.07.21-14.05.18:813][635]LogNet: UNetConnection::Close: [UNetConnection] RemoteAddr: , Name: IpConnection_2147482263, Driver: Name:PendingNetDriver Def:GameNetDriver IpNetDriver_2147482267, IsServer: NO, PC: NULL, Owner: NULL, UniqueId: INVALID, Channels: 3, Time: 2026.07.21-14.05.18
[2026.07.21-14.05.18:813][635]LogNet: UNetConnection::SendCloseReason:
[2026.07.21-14.05.18:813][635]LogNet: - Result=AddressResolutionFailed, ErrorContext="AddressResolutionFailed"
[2026.07.21-14.05.18:814][636]LogNet: Warning: Encountered an error, cleaning up this connection now
[2026.07.21-14.05.18:815][637]LogNet: Error: UEngine::BroadcastNetworkFailure: FailureType = PendingConnectionFailure, ErrorString = Your connection to the host has been lost., Driver = Name:PendingNetDriver Def:GameNetDriver IpNetDriver_2147482267
[2026.07.21-14.05.18:815][637]LogNet: Warning: Network Failure: PendingNetDriver[PendingConnectionFailure]: Your connection to the host has been lost.
[2026.07.21-14.05.18:815][637]LogNet: NetworkFailure: PendingConnectionFailure, Error: 'Your connection to the host has been lost.'
[2026.07.21-14.05.18:815][637]LogGameMode: Display: Match State Changed from LeavingMap to Aborted
[2026.07.21-14.05.18:815][637]LogGameState: Match State Changed from LeavingMap to Aborted
[2026.07.21-14.05.18:815][637]LogNet: DestroyNamedNetDriver: Name:PendingNetDriver Def:GameNetDriver IpNetDriver_2147482267
The log mentions IpNetDriver instead of SteamNetDriver which makes us question that something might have changed.
Our Config looks like this:
[OnlineSubsystem]
DefaultPlatformService=Steam[OnlineSubsystem]
DefaultPlatformService=Steam
bHasVoiceEnabled=true
VoiceNotificationDelta=0.2
MaxLocalTalkers=1
MaxRemoteTalkers=16
PollingIntervalInMs=20
bUseBuildIdOverride=false
BuildIdOverride=0
!AdditionalModulesToLoad=Clear
+AdditionalModulesToLoad=HTTP
+AdditionalModulesToLoad=XMPP[OnlineSubsystemSteam]
bEnabled=true
SteamDevAppId=12345
bInitServerOnClient=true
bUsesPresence=true
bUseLobbiesIfAvailable=true
bUseSteamNetworking=true
bAllowP2PPacketRelay=true
Achievement_0_Id=[/Script/OnlineSubsystemSteam.SteamNetDriver]
NetConnectionClassName=“OnlineSubsystemSteam.SteamNetConnection”[/Script/Engine.GameEngine]
!NetDriverDefinitions=ClearArray
+NetDriverDefinitions=(DefName=“GameNetDriver”,DriverClassName=“OnlineSubsystemSteam.SteamNetDriver”,DriverClassNameFallback=“OnlineSubsystemUtils.IpNetDriver”)
and the Build.cs contains the following:
PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "AdvancedSessions", "AdvancedSteamSessions" });
PrivateDependencyModuleNames.AddRange(new string[] { "OnlineSubsystem" });
DynamicallyLoadedModuleNames.Add("OnlineSubsystemSteam");
Does anyone have an idea whats the iossue is?
Thanks!