To establish a connection between client and remote host, you are expected to go through a coordination server which you trust, that can be either the official

To establish a connection between client and remote host, you are expected to go through a coordination server which you trust, that can be either the official one or your own self-hosted instance. Your client and the remote host will then attempt to directly connect if possible, only actually sending the display and input streams through a relay server if a direct connection is impossible due to NAT or whatever else. The use case where encryption is not supported is directly connecting by IP address, which is not the intended use for this software. It's an open source analog to TeamViewer, not a replacement for VNC or RDP. The direct connect functionality is there primarily for testing, which is why it's entirely disabled by default and the option to turn it on is buried at the bottom of a dialog that requires elevated privileges to access. If your use case is focused on those direct connections, RustDesk is not aimed at you.