Freeze when jumping timeline on web browser

[Chaperone]

Thank you very much for your reply and support.

I tried with:

Code:

sudo docker exec -it jellyfin bash
/usr/lib/jellyfin-ffmpeg/ffmpeg -fflags +genpts+igndts -i "/container/path/to/problem/video.mkv" -map 0 -codec copy -max_muxing_queue_size 2048 -max_interleave_delta 0 -avoid_negative_ts disabled newFile.mkv

I tried on Edge and Firefox, with different behaviors.
 
On Edge using either MP4 or MKV remuxed:

• I can move the time cursor for the first time, and if I try to move it again, the video freeze.
  
• After the video continue the playback, I can move AGAIN the cursor, and the video continues on the first time... But if I try again, the video freezes again.
  
• I have the same behavior either using the MP4 or MKV video
  
• Maybe is faster the reposition of the time cursor while using MKV
  

On Firefox using MP4:

• Using the MP4 if I move the cursor over the timeline, two things could happen:
  
• 1. The video just advances ~1 minute
  
• 2. The video freezes, and never continue
  

On Firefox using MKV remuxed:

• Using the remuxed MKV file, work as OK. I can move the time cursor, and the video works.
  

The original MP4 video:

Code:

Playback Info
Player Html Video Player
Play method Direct playing
Protocol https
Stream type Video

Video Info
Player dimensions 1868x1466
Video resolution 1920x1012
Dropped frames 0
Corrupted frames 0

Original Media Info
Container mp4
Size 2 GiB
Bitrate 2.6 Mbps
Video codec H264 High
Video bitrate 2.2 Mbps
Video range type SDR
Audio codec AAC LC
Audio bitrate 384 kbps
Audio channels 6
Audio sample rate 48000 Hz

The remixed MKV video:

Code:

Playback Info
Player Html Video Player
Play method Direct streaming
Protocol https
Stream type HLS

Video Info
Player dimensions 1868x1466
Video resolution 1920x1012
Dropped frames 0
Corrupted frames 0

Direct Streaming Info
Video codec H264 (direct)
Audio codec AAC

Original Media Info
Container mkv
Size 2 GiB
Bitrate 3.0 Mbps
Video codec H264 High
Video bitrate 2.6 Mbps
Video range type SDR
Audio codec AAC LC
Audio bitrate 320 kbps
Audio channels 2
Audio sample rate 48000 Hz

Could it be the buffer takes TOO much time to fill the reposition of the cursor?
For testing, how can I increase the playback buffer?

By the way, I am using Direct Playing, because my NAS CPU does not support transcoding... Or I was not able to make it work.

Thank you for any ideas you could share.