Thanks for the reply. I found what the issue was and I explained on this thread how I fixed it.
Apparently, the scene name was null because this code: gameScene = SceneManager.GetSceneByBuildIndex(1);
does not retrieve the data correctly.
gameScenePath = SceneUtility.GetScenePathByBuildIndex(1);
string gameSceneName = System.IO.Path.GetFileNameWithoutExtension(gameScenePath);
on the other hand did the trick.
Appart from that, I want to ask something out of curiosity:
I tried loading the scene with the SceneManager and also with the NetworkManager, but I don’t see any difference, they look the same to me. Why is it recommended to do it with the NetworkManager?