Log

[2019.11.18-21.00.47:693][  0]LogTemp: Warning: Starting Play in Game Mode (in GameMode::StartPlay())
[2019.11.18-21.00.47:693][  0]LogLoad: Took 0.296172 seconds to LoadMap(/Game/FirstPersonCPP/Maps/FirstPersonExampleMap.umap)
[2019.11.18-21.00.47:694][  0]LogTemp: Warning: Successfully created a session, now starting it.
(called after OnCreateSessionCompleteDelegate_Handle fires, OnCreateSessionComplete(...))
[2019.11.18-21.00.47:695][  0]LogTemp: Warning: Online session has started
(called after OnStartSessionCompleteDelegate_Handle fires, OnStartOnlineGameComplete(...)
[2019.11.18-21.00.47:695][  0]LogTemp: Warning: Has a world, now traveling the server
(not traveling as the map is already loaded correctly same function, just to check whether OnlineGameComplete was successful)

Client connects to the server and it gives back these messages on the server log:

[2019.11.18-21.14.35:510][880]LogTemp: Warning: Prelogin Game Mode
(GameMode::Prelogin)
[2019.11.18-21.14.35:543][881]LogNet: Client netspeed is 10000
[2019.11.18-21.14.35:877][891]LogNet: Join request: /Game/FirstPersonCPP/Maps/FirstPersonExampleMap?Name=DESKTOP-PCNAME?SplitscreenCount=1
[2019.11.18-21.14.35:878][891]LogOnlineSession: Warning: OSS: No game present to join for session (GameSession)
[2019.11.18-21.14.35:880][891]LogTemp: Warning: Starting GameSession on client
(GameMode::PostLogin)
[2019.11.18-21.14.35:880][891]LogOnlineSession: Warning: OSS: Can't start an online game for session (GameSession) that hasn't been created
(Sessions->StartSession(SessionName); in PostLogin)