Here's some info that might be useful for some people if trying to stream video at home or off-site through a browser...
Often I will be at my girls house and we want to stream a movie or TV show from the NAS that is back at my house and this is where problems have risen. I can't remember when but Synology changed the Video Station app and stopped allowing the streaming of certain videos through the browser. I started getting errors like "Failed to play the video because the file format of the currently selected audio track eac3 is not supported...". If you're running into this error I have a solution for you. Even if you don't use Video Station you have to have it running. I never use the app itself as I could never achieve the results I wanted and it was terrible at sorting my extensive library. Plus I can't passthrough HD audio. That's what I use Kodi for anway. So, typically I use File Station to browse to a video I want, right click on it, and then press play and play it through the browser. If you're getting the error above or something similar, here is a workaround for you.
You have to use an older version of Video Station, specifically (VideoStation-x86_64-2.3.4-1468.spk). So, you'll have to uninstall and re-install the old version. In addition to that you need to install FFmpeg package from the SynoCommunity (
https://synocommunity.com/). After that, you should have no problem playing videos through the browser or on your phone.