Tl;Dr: In the settings if the Plex app, make sure you force Direct Play instead of Auto.

I have a Roku ultra I stopped using in favor of a Shield TV a while ago (which is a much better experience, by the way), but I recently added a monitor to my workout room and I didn’t really want to spend $50 on a Chromecast with Google TV so I decided to give the Roku another shot. Not only is it still not great, I discovered it wouldn’t even play 4k HDR video from Plex, which is what the majority of my library is.

Off to Google I went where everyone just said, “Set the video quality to Original”, which is what I was trying to watch on. I didn’t really find anything else helpful online, so I just played around with the settings.

I knew my server could transcode the video stream, no problem, because I’ve done it many times (Nvidia P1000 is solid), but I figured for some reason the Roku just wasn’t happy with it and I decided to set Direct Play to Force. This does mean some media won’t play if it’s not supported, but that shouldn’t be much of an issue for me.

Hope this helps someone out there that also has a 5 year old Roku Ultra

– Zack