To enjoy Netflix in 4k resolution, several conditions must be satisfied.
You must have a Netflix account that supports 4k output. The basic level of Netflix account does NOT allow 4k streaming. To verify whether your account supports 4k, you should log into your Netflix account and check under the YourAccount section. Under Plan Details you should see 4 Screens + Ultra HD. This is currently the premium plan offered by Netflix and it does cost more than the basic 2 Screens plus HD plan that only supports 1080p. If you see anything other than “+Ultra HD” at the end of your plan, you can either upgrade your plan online in your account or contact Netflix for any questions you have regarding the plan differences.
You must make certain that your settings for content streaming allow for Ultra HD resolution. To do this you will again need to log into in your Netflix account. Select “Playback Settings” under your profile. You need to select “High” Data Usage.
You also need to make certain that your internet speed will allow Ultra HD (4k). You need at least 7GB per hour for 4k and 3GB per hour for HD
Finally, you actually need to select content that is recorded in 4k. Not all Netflix videos are recorded in 4k so you will want to check for the titles that are. Netflix has a link here that will list their current 4K offerings: http://www.netflixupdate.com/4k-movies-on-netflix-list/