I have the serve running on a DS214Play. I spent september out of town with the device shut down. I can't remember the last time I got a new subtitle, but I'm sure nothing that I uploaded to it after October 3rd got any subtitles downloaded. I see it's happening on linux too.
2015-10-26 11:15:17,352 (-4b0ff490) : DEBUG (networking:166) - Requesting 'http://127.0.0.1:32400/library/metadata/1329/tree'
2015-10-26 11:15:17,382 (-4b0ff490) : INFO (__init__:53) - Existing token found. Revalidating.
2015-10-26 11:15:17,912 (-4b0ff490) : INFO (__init__:76) - Valid token.
2015-10-26 11:15:17,916 (-4b0ff490) : INFO (__init__:116) - Looking for match for GUID 22924cb29e4b4aed and size 870105112
2015-10-26 11:15:18,186 (-4b0ff490) : INFO (__init__:154) - No valid subtitles. Skipping.
2015-10-26 11:15:18,197 (-4b0ff490) : DEBUG (model:225) - Serializing to /volume1/Plex/Library/Application Support/Plex Media Server/Metadata/Movies/8/e6b135f78ccd5186d5c83478d34daa9851c5adb.bundle/Contents/com.plexapp.agents.opensubtitles/Info.xml
2015-10-26 11:15:18,206 (-4b0ff490) : DEBUG (runtime:918) - Response: [200] str, 16 bytes