Not sure about the color problems.
The Ethernet port on the TV is 100 Mbps. The TV’s Wi-Fi can connect at faster than 100 Mbps if there is a strong 5 GHz signal (802.11ac / WiFi 5).
Some 4K HDR Blu-ray rips can burst above 100 Mbps. If the TV is connected via Ethernet when this happens, you may experience buffering. Connecting via Wi-Fi may help.
“CPU not powerful enough” is Plex’s cryptic way of saying “I need to transcode the video and you have disabled transcoding.”
With the Plex app on LG TVs, if the media is direct streaming, such as when audio is transcoding, enabling any subtitle results in a video transcode.
Avoid TrueHD or other situations where the audio transcodes. Movies / TV shows released on disc with TrueHD audio also have a Dolby Digital (AC3) version of the audio track. Use the AC3 version if it is available.
You can monitor playback via Plex Dashboard → Now Playing + Expanded View. It will show you if the video or audio is transcoding.
Monitor memory usage by Plex Media Server.
There is a long standing memory leak bug in Plex Media Server on Linux. If the DLNA server is enabled and there is an LG TV on the network, PMS will slowly consume available memory on the server. Restarting PMS releases the memory, but the process will start over again.
