I'm surprised by your comment. I bought the 65E17NUS last weekend from JB Hifi and have been playing 4K YouTube clips most nights just to show the wife why we needed to upgrade! :-)
Mine is hard wired into the network and it seems to play them fine with no noticeable jerkiness or buffering. I'm only on VDSL as fibre is not available in our area yet but still getting around 70Mbps download. Not sure which firmware it is running as haven't seen any reason to check yet. I haven't tried Netflix to see if it gives me the option but will have a look.