Pokud se nemýlím, ta DS214 má CPU Atom a prostě 4K nezvládne.

DS214 play
Hardware HD video transcoding built into the chip
Hardware Transcoding Engine: H.264 (AVC), MPEG-4 Part 2, MPEG-2, VC-1

DS216 play
1080p H.264 and 4K H.265 Ultra HD video transcoding capabilities
Hardware Transcoding Engine: H.265 (HEVC), MPEG-4 Part 2, MPEG-2, VC-1, Maximum resolution: 4K (3840 x 2160), Maximum FPS: 30