Thanks to the both of you, fzinken and ActionA.
I am running a test for over an hour of constant playback now and no random stop occured.
Seems like the slow smb interface of kodi really might have been the reason for the strange behavior. So let’s hope it won’t happen again in the long run 
Thank you very much. I will keep you updated in case it happens again.
For people with the same issue stumpling about this topic:
mount the smb drives via fstab (Tutorial)