Synology 423+ Cannot Transcode 4k UHD to H264

Plex Media Server
1

Server Version#: 1.40.3.8555-7000
Player Version#: 4.129.1

According to the compatibility list my device should be capable of transcoding 4k UHD to H264: Plex NAS Compatibility - Google Sheets

I have enabled transcoding and see in the dashboard that it says Transcode (hw) for the video but don’t see the same for sound not sure if that’s the issue or something else:

Plex Web — Chrome

Paused—6:11 / 2:36:21

Local ()—10 Gbps

Video

4K HDR10 (HEVC Main 10) (hw)

4K (H264)—Transcode (hw)

Audio

English (DTS-HD MA 7.1)

AAC—Transcode

Subtitles

English (PGS)

Burn in

2

Reading through this post: HW Transcoding broken
It appears that the issue was due to burning in subtitles overwhelming the CPU. Disabled subtitles and the issue disappeared. So now my question is how to get subtitles working?

3

Synology CPUs are not powerful enough to burn in PGS.

Turn off the PGS subtitles and try again
-or-
use only SRT (no burn-in)

5

@DrYeerk

Before I forget, We are working on a reported problem with PMS 1.40.3.8555 and GeminiLake CPUs,

If you’d like a previous version, please let me know.