Lecture MKV / NAS

Hello to you,

Any idea, advice, how to play MKVs from my NAS server?

Network: “WD MyCloud” NAS connected via RJ45 directly to the modem. If all goes well, reading lasts 2 minutes then lags, freezes, etc. therefore unreadable. I read comments that the Plex app is to be tested but apart from an error message during installation I have nothing else.

THANKS!