マルチプレイのセットアップ

• Online Subsystem
• Online Subsystem Steam
• Steam Socket

• Steamをターゲットとし、EOSは使わない
• リッスンサーバー
• UE5.5

[/Script/Engine.GameEngine]
!NetDriverDefinitions=ClearArray
+NetDriverDefinitions=(DefName="GameNetDriver",DriverClassName="/Script/SteamSockets.SteamSocketsNetDriver",DriverClassNameFallback="/Script/SteamSockets.SteamNetSocketsNetDriver")
; 公式Doc通りだと以下
; [/Script/Engine.GameEngine]
; +NetDriverDefinitions=(DefName="GameNetDriver",DriverClassName="OnlineSubsystemSteam.SteamNetDriver",DriverClassNameFallback="OnlineSubsystemUtils.IpNetDriver")
 
[OnlineSubsystem]
DefaultPlatformService=Steam
 
[OnlineSubsystemSteam]
bEnabled=true
SteamDevAppId=480
SteamAppId=480
; GameServerQueryPort=27015
bInitServerOnClient=true
bUsesPresence=true
bUseLobbiesIfAvailable=true
bUseSteamNetworking=true
bAllowP2PPacketRelay=true
 
[/Script/OnlineSubsystemSteam.SteamNetDriver]
NetConnectionClassName="OnlineSubsystemSteam.SteamNetConnection";

DefaultEngine.ini で bUseLobbiesIfAvailable=true と設定しても、false となる。
JoinSession時に、bUsesPresence と FOnlineSessionSettings::bUseLobbiesIfAvailable

[FOnlineSessionSteam::JoinSession] The values of FOnlineSessionSettings::bUsesPresence and FOnlineSessionSettings::bUseLobbiesIfAvailable are treated as equal and have to match

    UFUNCTION(BlueprintCallable, Category = "VshsSteam|Session")
    static void FixSteamSearchResultFlags(UPARAM(ref) FBlueprintSessionResult& SessionResult);

void UVshsSteamFunctions::FixSteamSearchResultFlags(FBlueprintSessionResult& SessionResult)
{
    FOnlineSessionSearchResult& NativeResult = SessionResult.OnlineResult;
    NativeResult.Session.SessionSettings.bUsesPresence = true;
    NativeResult.Session.SessionSettings.bUseLobbiesIfAvailable = true;
}

• Standalone Game で実行して Steamオーバーレイが出るが、セッションを作成できない
  • Play As Listen Server でプレイしていないか？おそらくSteamNetDriver が 同じP2Pポートで2重Listenを試みて失敗