Obviously most users won't be able to do this, but this is exactly the type of reason I use OpenWRT on my RPi-based router. I have a firewall rule that prevents the TV from communicating with anything in the WAN zone. I can still have the TV on the Wi-Fi and still use features like Airplay.
I disable the firewall rule if I want to try updating the TV firmware.
That breaks the built in chromecast, right (since the TV is the one fetching the stream), but I suppose you could plug in a regular chromecast dongle if that matters to you.
Google may well be violating their privacy policy which specifically claims they don't do that, but I don't think it's likely; they run a pretty tight ship RE legal messaging, and _someone would have noticed_ since all you have to do is watch a video on a non-google property and watch the network traffic.
> my cable provider clT out refused to give me the PPP / etc details or I have to go find an RPi with adsl io.
In the USA and perhaps other countries the cable provider is required to let you use your own DOCSIS modem. The list of modems that work with their system has to be on their web site.
They don't want to do this because they are all shitheads and also because they want to charge you "rent". But TBF I imagine it's also because it's easier to debug customer support calls when they manage the whole connection (e.g. GF's kids complain that "WiFi is down" when they mean the cable connection is down).
Sadly, enforcement of this directive is up to each country's own regulator, and as the map in the above link shows, only a few countries have actually enshrined this in their national laws.
You can chain routers. disable the isp router's wifi, or just ignore it. Then place your router of choice on the LAN side of the ISP's router as the its Ethernet client. Make up a new subnet of your choice on your router's LAN side and use its wifi and DHCP.
See if your cable modem has a pass-through mode. This disables the NAT, DHCP, etc and passes the IP address of the cable side of the modem through to one of the ethernet jacks. Then you plug your own router in to that and do your own NAT, DHCP, firewall, etc. I know Arris used to have this, haven't checked recently.
My current ISP has the cable modem completely locked down. No control over DHCP, no punching service ports through the NAT for home servers. Also they've got me double NATed.
Add a second router and put it in your ISP router’s DMZ. You shouldn’t have trouble with double nat since all traffic will get forwarded on to your “real” router.
I disable the firewall rule if I want to try updating the TV firmware.