I checked this SiteMinder 12.5: Policy Server Unreachable and it slightly resembled my issue but in my case i'm able to access Admin UI by localhost and 127.0.0.1 .
My Policy Server and Data source connection is showing Test connection successful but when i execute the XPSRegClient, Siteminder Admin UI still shows server is unreachable.
Policy server and WAM UI are on the same server.
While trying to register the Admin UI to use it with FQDN ,
Tried smreghost command t manually enter the siteminder as a trustedhost but if also failed.
Executed the XPSReg command multiple times with no positive result.
Attaching the smps.log and XPSRegClient log file, yes XPSConfig and XPSExplorer option is working fine.