When viewing 4K content using the MediaZilla app, you will be able to choose between SD / HD playback or 4K playback if your streaming device supports 4K.
When viewing 4K content in a web browser, you will be able to set the playback quality in the lower-right corner.
The quality will default to Auto (adaptive), and can manually be set to any of the available encoded resolutions, including 2160p (4K Ultra HD).
In order to see the 4K 2160p quality option, your browser must support the HEVC codec. This codec is not supported in all browsers. However, the HEVC codec is currently the most universally supported codec for 4K across all devices (e.g. Apple TV, Amazon Fire TV, Android, iOS, Roku, etc.).
On Mac, you must use the Safari or Chrome browsers to see quality options above 1080p during video playback.
On Windows, you must use the Chrome or Edge browsers to see quality options above 1080p during video playback.