Plex will detect the bandwidth automatically.

When your Plex playback keeps buffering and lagging, the first thing is to check if you're on Ethernet or Wi-Fi. Do remember to restart the server after the purchase of a Plex Pass.

A recent device that support hardware acceleration or get a compatible NVIDIA to your NAS device.To get hardware acceleration for Plex, you need to have: The hardware transcoding is not a magic pill for smooth 4K viewing, but it can help fix some of the Plex 4K buffering issues. To fix Plex buffering errors with 4K videos, don't forget to enable the hardware acceleration for streaming. Fixes to Plex Buffering & Stuttering Issues

To save your time and efforts, here we have gathered the most possible solutions to Plex buffering issues with 4K, Xbox, TVs, etc. However, as Plex involves quite a wide range of devices and different operations, it's quite tricky to diagnose the problems. No matter you're using Samsung TV, Xbox One, PS4, Roku, etc., you will find that Plex is prone to the issues, especially constant buffering issues with large files like 4K. Plex buffering & stuttering issues are not a new topic on Plex and othe related forums. It's very annoying that the movie stops every minute for few seconds. I got a Synology DS718+ and when watching movies h.264 1080p on my Samsung TV QE55Q7, the Plex keeps lagging constantly. If I fast forward to half way, it will buffer forever. When I watch a 4K HDR file streaming from my Western Digital My Passport Wireless Pro to my LG OLED LG OLED55E6P using the Plex app, I get buffering throughout the film to the point where I have to stop watching it. Plex Buffering & Stuttering Issues with 4K, Xbox One

Plex app samsung tv not working