Oh, I see. The problem was an old Engine.ini that was in the Saved folder of my project. This ini file had the old SteamNetDriver inside the NetDriverDefinitions, which was messing with things - I think the editor was using this file instead of the DefaultEngine . Anyways, I saw that the game was trying to use the SteamNetDriver instead of the SteamSocketsNetDriver, so that’s how I got the root of the problem.
After deleting all Engine.ini files inside my project, the game worked inside the editor without this workaround.
Well, note to my self, be careful with stuff inside the Saved folder when testing inside the editor.