I would guess you’re probably overestimating how much power is needed to run Zwift well, or vastly overestimating how much is needed to match an Apple TV. Used desktops that can do the latter are readily available, though the smallest are proprietary inside, like this HP for £49 (and accepting offers) which is about a foot square and 4in tall: HP ProDesk 400 G2.5 SFF PC Intel i3-4170 3.70GHz 8GB RAM 128GB SSD Win 10 Pro | eBay Not great as an investment but does the job.
Anyway just some ideas. A NUC is completely unsuitable for running any 3D game though.
So, an update.
Zwift support got back to me and suggested a few things but nothing really substantial. I thought they might get me to try to Telnet to an IP on a specific port. Didn’t get anywhere and seemed there was little hope of it getting resolved.
So, rather fred up, I headed down to an Apple store near me and bought a new ATV 4K. I saw some older ATV that met the minimum reqs on eBay for about £60 but was worried about long term support and, well, just failing. Pay cheap, pay twice.
Got home and set up the ATV very quickly. Installed the app, moved the Zwift Hub into range and all sorted out in less than 15 mins. HRM detected and working too, which was a slight concern.
Picture was great on my old 42" 1080 TV.
It just worked. I’m glad that you had the same experience when using a Mac or PC but that was far from my experience.
Thanks for your suggestions though.
For clarity I was referring to the in-game experience in terms of graphics and frame rate performance. An equivalent PC setup (i.e. dedicated for Zwift) takes some basic setting up initially and most people don’t want to do this.
Anyway glad you’re sorted.