What takes the brunt of playing an HDR movie on plex, network or TV or server? Odd question I know -- but I currently use a regular PC as my plex server, storage is a 4TB external hard drive. It works fine 90% of the time, but since I got an LG OLED last year, I got a decent amount of HDR files but when I get into the large movie files with extremely high bitrates it lags so much it can't be played. My question is what causes this? The TV and the Plex App on it? The fact it's streaming over my network wirelessly? Or the PC that the Plex server runs on? Or all of the above/none of the above? 

For example. I have an 120gig file of Ready Player One from last year with HDR, the bitrate is the highest i've ever downloaded and when I play it , it can't go more than 10 secs without buffering. Same with The Martian, around 70 gigs with slightly less bitrate. 

Anything I can do to rectify it? I was told to try X-Play app because it handles HDR better, but no luck there.