SOLVED: Straming issues with large files HEVC HDR10+

[yodamin]

Hi,

I am new so - first post.
Please slap me if I got the wrong category :-)

Whenever I play a large'ish 4k mkv HDR 10 or 10+ file I get stuttering within 1 minute of start.
Up to 1 minute it is smooth as butter.

I have an 8700K, 32GB RAM, 512GB NvME for EndeavourOS and a 12TB mechanical drive for my media (Seagate Iron Wolf 12 TG 7200 RPM)
mounted via fstab with noatime set.

The movie is being transcoded into AV1/AAC 2 ch 25.4Mbps 57fps and I am using my Firefox web browser to test this on my desktop.

I am on an internal 1Gbps LAN and the server and client are separated by a switch and about 5-6 feet.
All connections are wired. For now. When this is all worked out I'll have wireless 6g clients using the server also.

For example the movie below: starts to stutter within 50 seconds of starting the movie and does not stop. When I play it remotely from the same server using vlc it is fine. NO transcoding and no stuttering at all.

Any help at all would be much appreciated. 
TYVM everyone.



The Usual Suspects (1995)
Container: mkv
Path: /mnt/Media/movies/The Usual Suspects (1995)/The Usual Suspects (1995).mkv
Size: 19002 MB

Subtitle
Title: English - Default - Forced - PGSSUB
Language: eng
Codec: PGSSUB
AVC: No
Default: Yes
Forced: Yes
External: No

Video
Title: 4K HEVC Dolby Vision Profile 8.1 (HDR10)
Codec: HEVC
AVC: No
Profile: Main 10
Level: 153
Resolution: 3840x1600
Aspect ratio: 2.40:1
Anamorphic: No
Interlaced: No
Framerate: 60
Bitrate: 25131 kbps
Bit depth: 10 bit
Video range: HDR
Video range type: DOVIWithHDR10
DV title: Dolby Vision Profile 8.1 (HDR10)
DV version major: 1
DV version minor: 0
DV profile: 8
DV level: 8
DV rpu preset flag: 1
DV el preset flag: 0
DV bl preset flag: 1
DV bl signal compatibility id: 1
Color space: bt2020nc
Color transfer: smpte2084
Color primaries: bt2020
Pixel format: yuv420p10le
Ref frames: 1

Audio
Title: DD 5.1 - English - Dolby Digital - Default
Language: eng
Codec: AC3
AVC: No
Layout: 5.1
Channels: 6 ch
Bitrate: 640 kbps
Sample rate: 48000 Hz
Default: Yes
Forced: No
External: No

Audio
Title: DTS-HD MA 5.1 - English
Language: eng
Codec: DTS
AVC: No
Profile: DTS-HD MA
Layout: 5.1
Channels: 6 ch
Bitrate: 3790 kbps
Sample rate: 48000 Hz
Bit depth: 24 bit
Default: No
Forced: No
External: No

Audio
Title: DTS 5.1 - English
Language: eng
Codec: DTS
AVC: No
Profile: DTS
Layout: 5.1
Channels: 6 ch
Bitrate: 1536 kbps
Sample rate: 48000 Hz
Default: No
Forced: No
External: No