So, how does the Roku say it's talking to your TV (Settings/Display type)? Does it show and will it let you select a 4K type? If not, how is the Roku connected to the TV? Direct? Via an AVR? Are you using high-speed HDMI cables? How long are they?
YouTube requires a pretty robust Internet connection, and it's more than speed. When I was staying in a hotel for an extended stay, I had Internet that tested between 15-20 Mbps, but it was rare that I saw full 2160 on YouTube. That speed should have been sufficient, but there was something else. I was also running through a double NAT, as I built my own private network that connected to the hotel Internet. Now that I'm back home with my 60 Mbps speed, and only the normal single NAT, I get 2160 immediately on my Rokus that support it (Ultra, 4 and TV).
YouTube calls it "Stats for Nerds". I qualify, because I'm always checking it.
Any ideas, help?
The YouTube app on LG webos has no issues displaying full resolution with HDR over wireless. The roku box is wired.
Netflix plays 4K HDR through the lg webos app with no issues, same with Plex and the YouTube app from LG. It’s just the roku Ultra displaying these videos at 1080p.