Your Smart TV is smarter than you think
I started to investigate a little bit of the actual traffic that is going on from the everyday devices you connect to your home network.
Since the end of last year I have set up a Raspberry Pi with a running Pi-hole Ad blocking service in my home network. Troy Hunt wrote a nice article about the (w)hole thing if you want to setup your own: Mmm... Pi-hole...
The most interesting thing about having a Pi-hole setup as DNS server for your network is that you can see what your other devices are doing.
For example a Samsung Smart TV in my case:

And this is not even all. I just searched for domains with samsung
in it. It had to connect the TV to the Internet because of Youtube and Netflix but I blocked now all hosts which I could identify as related to the TV and not necessary for streaming movies.
Learning: Be careful with all the fancy devices you connect to your home network. And use a Guest Network when available.