Relay is only intended to transmit multiplayer game states, such as stats, resource counts, unit locations, and so on. Using the Relay service for other types of data transmission is not permitted and could lead to termination of service. This includes, but is not limited to:
- Audio and video streaming
- Voice chat
- File transfer
- Proxy and VPN services
Unity offers a number of game services that may be a better fit for the feature you are trying to implement. You can read more about these services on the Game Services homepage, or within the Unity Dashboard.
See the Relay documentation for more information on limitations and fair usage.