file video stopped working

Hi everybody.....mi child is used to watching the same cartoon several time. The .mkv file is stored on my nas Synolgy and with serviio on docker for the broadcasting of the videos.
Two days ago the LG tv give an error "unsupported file"........but it's the same file, on the same server, with the same sistem....of the previus time.
What happened? Any suggestion?
Thanks, Gianluca
Two days ago the LG tv give an error "unsupported file"........but it's the same file, on the same server, with the same sistem....of the previus time.
What happened? Any suggestion?
Thanks, Gianluca