www.makemkv.com

I prefer to watch videos using the built-in application on my LG C7 OLED to access files on my Synology NAS.

I just started using my new LG WH16NS40 to convert my UHD collection to MVK. When I use VLC player on my PC the subtitle track is included. However, when using the LG TV app to access these same files the subtitle button is grayed out.

I have an Apple TV 4K and Firecube streaming devices but not sure how to access NAS files on these devices nor whether this will resolve the missing subtitle tracks. I would prefer to keep using the LG TV app, but not sure why subtitles can appear on some video tracks, but not on the ones I made using MakeMKV.

Any help appreciated.

As a newbie, I probably can't help, but I have a question:
What steaming service are you running on your NAS (i.e. "Plex", "Jellyfin", etc.)?
I am familiar with Jellyfin, and might be able to assist.

I am not using any streaming service on the NAS, just using it as a straight file server.

I also use "just a file server" for the source of my MKV (and MP4) files.

For Amazon Fire devices, I use ViMu, which can open "regular" file servers and play video. I've also used VLC, but ViMu just works better for my tastes.

For Apple devices, VLC works, but it wants to log in to the SMB device to play videos. Once past that, it work OK.

On Android, I use a program called "BubbleUP" to feed VLC. I could probably use VLC directly, but I've used BubbleUP since before I had an Andoid phone, so I continued to use it on the phone too.

All that said... streaming to "just" a TV affects subtitles on both MKV and MP4. The ORDER of the subtitle tracks affects visibility for some apps. Some will only see the first one, so you can't select them, and some disks you rip from put the "wrong track" in as the first subtitle track. Using external tools (like mkvtoolnix or handbrake) allow you to choose the order of tracks, when that is a factor.

Thanks Woodstock! I tried VLC on APTV and the subtitles do display properly. I haven't tried using ViMu yet, but since I have just enough coins to get it for free, I may just try it to see what I like better.