Next time, make a VLAN with its own Wifi, then connect the TV to that VLAN and then what you want to do is block any incoming or outgoing network traffic to the smart TV. If you do this then no one else can attempt to hijack or connect to your TV and the TV wont ask you to connect it to a network, because its already connected to a network. This worked great on my LG smart TV.

What is the point of doing this as opposed to just skipping that step? Does it keep nagging you? Or are certain features disabled if you don't connect?

I don't own a Smart TV, but without this step I'd be very suspicious that the TV would silently try to connect to open wifi networks, or perhaps some kind of hotspot like xfinity or AT&T that the manufacturer made an agreement with.

Won't they just use Ethernet over HDMI?

Maybe, but that would only work if there is Internet at the other end of the HDMI.

Oh FFS I just learned this was a thing, I can't even trust my cables anymore.

Be aware that your ethernet cables could also be powering stuff, so that's another cable to watch out for ;)

Watch out for the reverse too, ethernet over powerline is a thing!

I would skip the VLAN step and just block communication from the TV to the internet. That way you could still access media on other devices on your lan via DLNA or something

What happens when you want to use Netflix, Amazon prime, or an external Plex server with the smart TV? You NEED internet access for those

Separate HTPC box that you trust?

My ideal TV has power and video in and nothing else. Basically a monitor. I have a separate box for content and another for input switching.

FYI you can't use an internal Plex server either. The Plex client is unable to operate without an Internet connection.

Chromecast or Roku

That's cool. I also saw someone mention PI-hole. I'd pick whichever method is easiest to setup for my parents, and lowest-maintenance so they don't have to call me. ;)

My network is setup like this. It is really easy to do if you have a good router/AP, but most consumer routers, especially the ones provided by ISPs, are not vlan aware.

Is it specific to the router? I've got a Ubiquiti Amplifi and I'm not totally sure of the proper way to do this.

Usually you define the vlan on your router/switches and then link a SSID to that vlan on your AP(s). Exact steps differ significantly between vendors.

My friends think I'm nuts for not having my tv connected to the network (I use my PS4 for all the offerings). It's just a default that people nowadays because it's convenient.

Yeah, how dare they, you barely got out of there with your life...

Seriously, the melodrama people treat their privacy with is frequently astounding.

I don't understand your criticism. If the TV were given close to free and then subsidized by ads, sure. But I'm paying >$500 for the TV, why should I get ads too?

Because they can. Alternatively, perhaps it would be more like >$2000 to avoid the advertising.

Or it would be $500 and no advertising. Them doing ads doesn't mean they can't survive without them, it just means they like the extra money.

My criticism is the vast overvaluing of information value, and the complete failure to accurately assess the risk of that information becoming public.