I followed this series of videos https://www.youtube.com/watch?v=abmzWUWxy1U&list=PLZlv_N0_O1gYqSlbGQVKsRg6fpxWndZqZ in order to set a stable networking system (Server - Client etc) and character select functionality for my project. The main changes by now are a) reparented my characters to a 0_Base character and b) set as Default Server Level the MainMenu level (a level that handles the server functions and umg), c) I reordered my widgets and addes custom events into my Game Instance.
When I tried to test my good old play level (and only my play level which I thought that was not largerly affected by the changes I made, following the videos) in editor, the Server player could not execute its commands (spawn of events and elements) and the Clients couldn’t display the health and stamina bars. I tested the my characters in another test level inside my project and all worked perfectly.
So the common node of these funcionalities was the Get Player Character which was referred to my current player… I changed the Index from 0 to 1 to my player character and the widgets and boum all worked fine…
I temporarily fixed it but what is going on with the networking changes to Indexes? are there any tutorials or sources so I can understand how this works and set my Get Player Character and Get Player Controller nodes properly? Did the reparenting of my characters caused the change to the Index?
Multiplayer stuff is highly confusing at the beginning, do not feel bad 
The BP Multiplayer Page is a great read and explains what runs/exists where.
In network multiplayer, index 0 is always the local player controller. Don’t make any assumptions about the order of any other controllers. In fact, only the server has all the PlayerController, the clients only have their own controller (!).
If you had to fix something by changing the index, you might have done something on the server which was supposed to run on the client (?).
Of course, that does not apply to local multiplayer (splitscreen), where more than one playercontroller are local.
Thank you for the responce but… I have read this one but nothing really applies to my project. The character in server mode spans event using a dropdown menu that sets true the proper elements and a left-click event spawns them. I haven’t used any custom events on this one. Maybe should I?
I could call a Multicast event when the left click event is pressed?
So there is there any chance I need to adjust character index? I feel I have missed something…