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.

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.

I use Arch because it makes installing almost any software package trivially easy via the AUR and if you run into issues, the wiki is there to help.

You should try out KDE in a Live CD. The snapping and tiling features work very well, Windows needs to catch up

Pinhole has allowed custom local records for a very long time now

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

It is paid for, with your time ;)

Higher end cable testers can show you where the break is, but it will be far more expensive that a new cable.

Jellyfin? It’s always supported 4K afaik