I would first check and make sure the game mode you’re trying to use is selected when you have the level open in the details panel… Secondly make sure that the correct default server map is selected in project settings.
If it is a driver issue and you’ve built a dedicated server it may be an .ini configuration issue and need to specify the correct net driver in there. Especially from what you have configured in the source in Visual Studio. You can have conflicting .ini configurations and have problems for sure.
Im not sure how you are connecting to the server map so that’s a little suspect here also. You shouldn’t be able to travel to the server map unless something else is going on when travelling and or connecting to the map.