NAS 540 Twonky and video-App tell "no data", but in databrowser i see all data

For a long time I have not changed anything on my NAS. Suddenly I can no longer access my data via Twonky, so the TV also shows "no data shared" for videos, music and photos. However, access via the file browser on the NAS works fine, even from the PC via samba all right.
I had that a few weeks ago, then the problem just disappeared - as it had come.

#NAS_Jan_2019