Hey
@Moritz_Bunkus I found a solution.
First I checked and tested with different accepted SMB protocol versions on my QNAP, but this was the false path.
Second I tried to connect to another SMB Share on a Windows VM, but this wasn’t working too.Then I tried to modify the username from “testuser” to “testuser@x.x.x.x(hostname/IP)” and the connection was established.
I modified the other credentials, and all connections are established now.
I don’t know why I had to modify all credentials, because it was working until the update, but now it is working again.
My Owncloud client on my Windows Notebook has a problem (allegedly all files were deleted from the server and the client asks me if I will delete all my files too, or keep them and upload to the server again) but this is no big problem for me. I stopped the synchronization for this profile and set up a new profile (with the same user account), started a new synchronization and when this is complete, I will delete the old profile.
Thank you very much for your help.