It can depend on the source. Does it say "this function isnt available"?
Yes and it is disabled with both my FIOS box and my Oppo UDP-203. My Yamaha RX-A3060 is set for Direct video. This capability on the Samsung has come and gone before and I thought it was based on a firmware update.
I give up. I have tried both wired and wireless connections, but I cannot seem to cross 22 Mbps with the Netflix app. I'm subscribed so I can get the 4K feed, but I don't think it's coming through. I have plenty of speed otherwise, as this was taken from my iPhone in the same spot as my TV:
Wired I can get about 60Mb but my phone and tablet easily get over 100Mb at the same location. Most of the time I'm in the 40Mb range which seems to be fine for 4K. Not sure why when it's wired I'm not at least getting 100Mb which should be the minimum for an Ethernet adapter from the last year. My guess is Samsung just put in the worst network adapters they could find so they could save a few bucks. It's also possible the apps don't report the proper speeds. Have you tried the browser and going to https://Fast.com which is run by netflix?
There is no "best", best is what's best for you...