Issue reported after an upgrade from Director 2203 to 2402 CU3.
Communication to the Director server is blocked by a proxy . The solution is for Director traffic to avoid the proxy.
Add below lines to C:\inetpub\wwwroot\Director\web.config
<system.net>
<defaultProxy>
<proxy usesystemdefault="false" bypassonlocal="true" />
</defaultProxy>
</system.net>
Backup C:\inetpub\wwwroot\Director\web.config as a precaution.
Lines need to go exactly in this location at top of C:\inetpub\wwwroot\Director\web.config.

Ensure there is no web.config located in inetpub\wwwroot folder.
Do an IISRESET and try to logon again.
Unable to logon to Citrix Director.
“The system is currently unavailable. Please try again later or contact your administrator”
