Most likely you need to port forward this port
Or not sure if you have it on same machine as server, you might be able to use local ip or localhost instead of your public ip
And maybe then you would not need to port forward, but not sure.
In your Source-Server-Relay.cfg
rf_scr_host localhost
or
rf_scr_host 127.0.0.1
If port forwarding, its possible you might need to do it on your router and also on windows firewall
https://www.noip.com/support/knowled...warding-guide/
https://portforward.com/
Windows firewall
https://www.softwaretestinghelp.com/how-to-open-ports/