Pretty much all current Synology DiskStations and RackStations can function as a media server, including to an Apple TV, but I personally found it very difficult to find an actual "how-to" guide and wasted a lot of time trying to figure it out.
Connect to a remote Synology via AppleTV | MacRumors Forums Aug 24, 2015 DS214play, Apple TV and DTS: my solution - Synology Forum Aug 23, 2014 The best way to watch media on the new Apple TV: iTunes The Apple TV streams content from your iTunes library, or directly from the iTunes Store, for previous purchases or rented movies, as well as streaming from Apple Music. Plex is a “media server Synology DS video and DS photo for Smart TVs - ACE
Jun 17, 2020
Review: Synology D1019+ Network Attached Storage device
Can I use a Synology to stream music to my Apple TV and
*You must own a Synology NAS to run this app and be running the latest Photo Station 6.6.0 package to get the complete set of features** DS photo allows you to browse through the photo collection