It’s not working here either (unsure which model we have, probably 2014 or 2015). I wonder if the older models of Samsung TVs don’t support the TLS encryption being forced by CloudFlare.
Aaand Bingo. I disabled CF routing and the server is now visible by the SmartTV client. Looks like your best option is going to be rolling your own reverse proxy on your own VPS where you can dictate the security headers if you want to keep the SmartTV and utilize a “CDN” of sorts.