Streaming over webdav(https) and no subtitles

I am running an ubuntu server on my old netbook and using Kodi to stream videos from it.
I have Kodi on my computer, smartphone, and my Android tv.
Everything works flawlessly; I can stream videos from everywhere and it’s really nice.
But I have a tiny problem. When I stream videos over smb, sftp and nfs, kodi automatically loads the corresponding subtitles that are in the same directoy. But over https (webdav), no subtitles appears and I have to manually load them on my android devices.
Funny thing is that on PC, it works just fine. Kodi automatically loads subtitles when streaming over https.
I don’t know if it’s the settings that I have wrong on my android devices or it’s a glitch affects only android devices.

And i wonder if there’s anyone else having the same problem.

P.s. I am running Kodi 16.1 on my phone btw.