After a few days of trying, I began to think that there was something wrong with my own project skills, so I created a new test project. I quickly opened it through the desktop 4.25 engine, but did not open the epic client. stay DefaultEngine.ini The code in the official online subsystem steam document is added in：
[/Script/Engine.GameEngine]
+NetDriverDefinitions=(DefName=“GameNetDriver”,DriverClassName=“OnlineSubsystemSteam.SteamNetDriver”,DriverClassNameFallback=“OnlineSubsystemUtils.IpNetDriver”)
[OnlineSubsystem]
DefaultPlatformService=Steam
[OnlineSubsystemSteam]
bEnabled=true
SteamDevAppId=480
[/Script/OnlineSubsystemSteam.SteamNetDriver]
NetConnectionClassName=“OnlineSubsystemSteam.SteamNetConnection”
Three plug-ins of onlinesubsystem steam sockets steam shared are opened to run the window independently, but they are still unsuccessful.
I used my own project to follow the above steps, and the package was not successful
I can work on 4.24 and below，Neither 4.25 nor 4.26 is acceptable