tested on Redhat 9 using Rustdesk v 1.2.3 (installed on AWS ec2 instance t3.micro)
installs Signal + Relay server
on the cloud instance where this is installed, configure iptables
### RustDesk relay
-A INPUT -p udp --dport 21116 -j ACCEPT
-A INPUT -s 0.0.0.0/0 -p tcp -m multiport --dports 21115,21116,21117 -j ACCEPT
make sure to open up SecurityGroups for these ports (if not using AWS, similar firewall groups in other providers)
on your desktop, open RustDesk, click on 3 dots next to your ID, go to Network section, for "ID server" add the public IP of your cloud instance (relay server)
your RD session should now flow via this cloud instance