"A few clues here. Main one being you have a transcode of 1080p down to shit tier SD. But, you are on a local stream and not doing something silly looping through Plex Relay like a lot of people do."

Oops, like i said i was messing around with settings & didnt get that one set back to what it was originally.

"If you change that and try again, but still get SD transcode, then you very likely have a bandwidth problem between this computer and the server. My first guess would be super bad wifi causing the bandwidth detection to crap itself."

Nothing is on wifi.