A basic first thing to try is going into your Settings >> Application manager and after selecting 'Netflix' tap the 'Force stop' button and then the 'Clear data' button. If that doesn't help do the same steps over again but also tap the 'Clear data' button. (but note when you 'Clear data' you'll have to re-enter your user I.D. and password when you launch the Netflix app)

 

Not sure if related to your issue but Netflix has had some issues in the past 24 hours


http://downdetector.com/status/netflix

 

Did you flash a custom ROM on your S6?

Netflix also just had a new update recently

 

Hey, first of all check your internet speed and then check Netflix server response on this website www.Netflixdown.com.

 

This is a dated thread, prior to Netflix killing off support for rooted Android devices:
https://www.theverge.com/2017/5/15/15640820/netflix-blocks-app-rooted-android-devices
You might try this workaround:
https://forum.xda-developers.com/apps/magisk/module-netflix-enabler-enable-netflix-t3708126

Just anecdotally, on an old, rooted phone Netflix is still working for me without having to do any tweaks to it, but it's version 4.16.0 (current is 6.5.0) so while I still use it to do stuff like watch content on a Chromecast each night, a lot of features and its user interface is less functional than when using a non-rooted, more current phone.