Turn off Verbose logging. Debug only.
Play without subtitles. This is forcing the video to transcode. You lose HDR and transcoding can cause buffering if it maxes your CPU/GPU at 100%.
Aug 15, 2019 14:20:13.484 [13912] DEBUG - MDE: Aquaman (2018): selected subtitle cannot be converted to a compatible format, burning into video stream
Aug 15, 2019 14:26:51.378 [14244] DEBUG - MDE: Dunkirk (2017): selected subtitle cannot be converted to a compatible format, burning into video stream
Select an AC3 (Dolby Digital) or EAC3 (Dolby Digital Plus) audio track if possible. Your TV most likely does not support TrueHD audio, forcing PMS to transcode it to a supported format. It also appears the TV does not support dts audio, which is hard to avoid, but do so if possible.
Aug 15, 2019 14:20:13.489 [13912] DEBUG - MDE: Cannot direct stream audio stream due to codec truehd when profile only allows eac3
Aug 15, 2019 14:26:51.383 [14244] DEBUG - MDE: Cannot direct stream audio stream due to codec dca when profile only allows aac
Is your laptop connected via wired or wireless? It should be connected to the network via wired Gigabit Ethernet if possible when in use as a Plex server.
Play one of the movies - AC3 audio, no subtitles.
During playback, check status on the Plex dashboard. Plex Web -> Activity. Does the video and audio direct play / direct stream / transcode? You may have to click on the gold box with two lines underneath to expand the view to see if things are transcoding.
Ideally, you want to find a movie that direct plays both audio and video and see if the movie still buffers.
If things direct play, then your PC is probably not the cause of buffering. It takes very little CPU to direct play a video. A Celeron, or even less, is sufficient when direct playing. You can then look at things such as the physical network connection for your PC & TV if still buffering during playback.
