That might explain the problem. Assuming adguard returns an nxdomain for blocked sites then the devices will try with their secondary DNS server and get to the blocked site

Sorry I misread your post. You shouldn’t need the 172 address in your DNS config, stick to the 127 address only.

In regard to the issue itself. Do your devices show their DNS server as the adguard server?

Your adguard config looks strange. The examples shown list different DNS providers but you have pointed it back at itself for its DNS. I don’t understand why you would do that.

My method to get around this is setting up a specific user account for my TV. In the user options you can disable transcoding

Jellyfin? It’s always supported 4K afaik

I like VueTorrent

https://github.com/WDaan/VueTorrent

Transcoding 4K isn’t as hard as you think. I used an i5-9500T and the iGPU could easily transcode ~80GB 4K Blu-ray rips at double real time speed. I’ve now switched to software transcoding on a 5800x and it also exceeds real time speed.

There are quite a lot of h265 HDR rips available now, particularly for newer series released on Netflix etc. They definitely support full 10bit HDR and look good to my eyes.