Buffering when watching 4K movies

Server Version#: 1.26.2
Player Version#: 5.38.1

Hello all. I’m trying to play 4k movies through the plex on my LG. The server is installed on my windows pc. I keep getting buffering, although as you can see, the speed is not even half as fast as peak. I don’t know what can be done anymore. Please help, thank you.

I connected my xbox through the gigabit port, I get all the same buffering, in addition, the plex transcodes 4k to 1080. my tv supports 4k, in the settings of the xbox everything is correct. i do not understand what is happening