I installed the latest (Version 1.1.4.2757) Plex server on my Diskstation 614+ --which happens to be the mapped-drive location for my Windows 64-bit Plex server installation--and it is NOT picking up correctly named and located .srt subtitles. Here's what I know:
The old Plex server still works fine finding and playing media files on the Synology NAS box and picks up subtitles fine. I have the Media & Agent settings set to look at Personal Media first for TV shows. The Languages setting is set to show subtitles always, etc. Actually, the latest version for Windows (1.1.4.2757) just picked up the same bug as the Synology of the same version has--you can't access the Languages tab from the local server web interface, so I'm taking it by faith that the settings shown in https://app.plex.tv/web/app#!/settings/server/fc-etc/languages is correct, as that is the only way to access that page for either my Synology server or my Windows 10 server.
I've checked every setting to make sure my Synology Plex installation exactly matches the Windows Plex installation. I'm pretty much out of ideas at this point.
SO--Windows picks up external .srt files fine on the same media library that the Synology can't. Synology does find embedded subtitles, of which I only have a couple.
Thoughts?