Whatever was on pastebin has been removed. You can attach log files to Plex forum posts. Just drag the file into the message window.
Do you have subtitles enabled? If so, turn them off and see what happens.
Plex may be burning the subtitles into the video stream. That uses the CPU, and if the CPU cannot perform the task in real time, you’ll experience buffering, timeouts, etc.
Also, when running Windows, Plex does not support hardware accelerated tone mapping when using Intel graphics. So, when transcoding HDR media, the tone mapping will also use the CPU.
You can monitor playback via the Plex Dashboard. It will show if the video or audio is transcoding and if subtitles are being burned into the video stream.
Regarding the clients you mentioned:
Roku: PGS subtitles are burned into the video stream.
LG: If the media is direct streaming, such as when audio is transcoding, enabling any type of subtitle results in a video transcode and subtitle burning.
