Is your Authentication Proxy a Windows server? Try opening an Administrator command prompt window and typing in netstat -a
. This will show you which services are listening on what ports. Look for 389 in the list.
Are you certain the Duo Security Authentication Proxy service is running? Try typing authproxyctl status
at the same command prompt to check.
Also, if you’re running Windows Firewall or another firewall on that server, double-check that your firewall rules permit inbound access on port 389 to the Duo Security Authentication proxy service.