Uninstalling the server will not fix issues with the Windows client app.
First thing I’d try is to delete the configuration file of the player software.
You should find plex.ini in
C:\Users\<windows_user_name>\AppData\Local\Plex
(Careful that the folder name is just “Plex”, and NOT “Plex Media Server”)
If you have previously modified the mpv.conf file, delete or move it as well.
After deleting plex.ini (or moving it somewhere else), your player will behave as if it was a totally fresh installation.
If you use an nVidia GPU, see that plex player will use the very default settings whioch you can set in the nVidia control panel under “3D settings”. If you have modified the global settings there, you need to either revert them, or create a custom profile just for plx player. Set everything to default, except the Energy saving mode, which you should try on “maximum”.
Once you have started the player and logged it into your plex account, enter the settings.
Settings - Plex for Windows - ‘Show Advanced’ - Player
Set the “Video Playback Quality” to “Normal”.
Do also try and toggle the “Use Hardware Decoding” checkbox.
Use a variety of differently encoded files to test after each change of the “Video Playback Quality”.
P.S: If you upgraded to a supported Windows 11 build just recently, you might be affected by the sudden absence of the Dolby decoder.
See [BUG] Problem with (E-)AC3 Codec and Windows update 24H2
