Hi Eric! In order for casting to work, both the TV and the mobile device need to be connected to the same network. Once connected, open the application through the mobile device, find the content you would like to play, and select the cast icon within the application. For additional support, please contact Samsung TV support at:
― Phone: 1-800-SAMSUNG / Available 8 AM - 9 PM EST, Mon - Fri
― LiveChat or Email: https://www.samsung.com/us/support/#contact_us_for_support
We look forward to hearing from you.
^Tim