I am using Plex server on Synology NAS, and connecting to WD TV Live Streaming as DLNA server.
The Plex server is configured to always show Hebrew subtitles (if was found on opensubtitles.org), and it is working fine (=Hebrew subtitles are displayed) when I play movies on my MacBook Air using Plex client.
Now, when playing with WD TV Live Streaming (from Plex DLNA server), I always see only English subtitles.
When I tried playing from network share with hebrew .srt file beside the .mkv, Hebrew subtitles are shown correctly,
So it looks like Plex can send subtitles, but always sending English version.
Also - when the movie is being played, I can't see any other subtitles options (I see only English and Off).