Both actually. They might need access to your internal network to access your file shares and whatnot, but you'll want to make sure they can access only the parts you want them to, and nothing else, so they can't for example log onto your unsecured printer and collect a list of most recent print jobs, including filenames.
And they might need to access the internet to download firmware updates and stream video, but you don't want them to "LG phone home" and report your midget porn viewing habits, so you'll block that.
Of course all that requires quite a bit of knowledge, time and equipment to set up and is therefore quite unrealistic, so you're better off just hooking up your laptop via HDMI and putting the damn TV into monitor mode, "smart" be damned.
And they might need to access the internet to download firmware updates and stream video, but you don't want them to "LG phone home" and report your midget porn viewing habits, so you'll block that.
Of course all that requires quite a bit of knowledge, time and equipment to set up and is therefore quite unrealistic, so you're better off just hooking up your laptop via HDMI and putting the damn TV into monitor mode, "smart" be damned.