VLC Media Player has been around for more than 20 years and I always found it to be superior to many other media players, especially when it comes to accessing the files on my NAS through Windows or Android devices. It has codecs that are missing on many other media players.
To use VLC on the Roku TV, one could use Google Chrome Cast and VLC on an Android tablet or phone. A better solution is to use the latest Google Chrome Cast device with Google TV. It is currently on sale for less than $30. Once installed on your Roku TV, go to Google TV and App search for "Android Apps" and select VLC from the list. You can then install the VLC app on your Chrome Cast device.
VLC's navigation of the NAS folders for video, music, and pictures is reliable, thorough and complete.