VLC for FireTV SMB Auth failed

[VanWebby]

Hi Everybody,
I have been using VLC on the FireTV Stick for a long time. So far, it always worked when I started VLC that I could connect directly to my NAS and was able to directly watch my films on TV.
Since yesterday, however, every time I want to connect to the NAS, he asks for a username and password, I enter both and click on Save password.
But he now requests username and password for every subfolder and file that I want to open. Often I also have the problem when I want to place the film in the sub-folder, I enter the access data, briefly see the sub-folder, and then it requests username and password again.
I never had the problem before, I only entered the username & password once and was then able to access and open every additional subfolder and every file in the folder.
What is wrong with me all of a sudden? Tried SMB1, SMB2, even SMB3 setting on my NAS, same problem everywhere.

For Information: I am using a Western Digitally MyCloud Mirror Cloud with 2x3TB