Hey everyone,
I need some help. I found out that lowering the graphic settings break the online gameplay even in a blank template created with 4.17 or my working on project from 4.15.
I created a thread for this here: [Serious Engine Bug] Graphic Settings break Network game! - Feedback for Unreal Engine team - Unreal Engine Forums
If anyone have the same issues, can reproduce them or not - all feedback is welcome.