Apple TV 4K is picky about the HDMI path in a way that looks like a software bug until you swap the lead. Match Content turns the room dark for a second, Dolby Vision fails to negotiate, or the sound bar eats eARC and the remote suddenly feels broken. Most of those tickets die when the cable between the box and the first display input is treated as infrastructure, not packaging copy.
Living-room racks rarely give you a clean one-metre run. There is usually a wall plate, a cheap switch, or a five-metre coil under the TV stand. Any of those can turn a certified Ultra High Speed cable into an expensive costume. Strip the path to source → one short certified lead → the HDR-capable HDMI input on the TV. If the picture cleans up, stop blaming tvOS for a minute.
Which port actually carries the features you paid for
Plenty of mid-range televisions only expose full HDMI 2.1 bandwidth and HDR on one or two labelled ports. The rest accept a picture and quietly drop dynamic metadata. Apple TV manuals are not the place to learn that map — the TV’s own input list is. Plug the streamer into the wrong socket and no “48 Gbps” jacket text on Amazon will fix the handshake.
Sound bars add another failure mode. When eARC and Match Frame Rate fight through a tired jumper, people reinstall apps. A better first check is whether the lead between Apple TV and the bar (or bar and TV) carries a real Ultra High Speed mark, not a marketing title. For a practical UK-facing walkthrough of that buying decision, see this Apple TV 4K HDMI cable guide.
A short A/B test before you buy another box
Keep one known-good short Ultra High Speed cable in the kit. Swap only that segment. Leave the Apple TV firmware alone until the cable path is boring again. If HDR returns and Match Content stops stuttering, you found the weak link. If it does not, then EDID, the display firmware, and the sound bar earn their turn — in that order.
Refuse unlabelled “8K ready” claims, coupler chains, and anything longer than the run needs. Prefer packaging that shows the Ultra High Speed certification mark. Treat the cable as part of the signal chain, and the mysterious Apple TV tickets get quieter.