Find a friend that also has Netflix on his Samsung TV.
- If it works there it's a problem with your TV, router, modem or ISP.
- If it doesn't work there either it's a problem with Samsung or Netflix.
You can try your own second Samsung TV also, but if none of those two it could be your router, modem or ISP also, althought that's unlikely if it's OK on your phone.
It's exactly the same as when not being able to visit a site on your laptop. Then you try somewhere else with your laptop. But a TV is somewhat more difficult to move, that's why you need a friend's TV now.
Kees