Note: When I login to each workstation and type in CLI (CMD)
wuauclt.exe /detectnow /reportnow
I am able to see these machines from the WSUS console but the other would disappear.
– Reason for unexpected behaviour
This happens sometimes to cloned servers because they are having the same SUSClientID. Each time the server contacts wsus, the entry in the WSUS console would get overwritten with the new server information and the existing machine would disappear.
Solution
Navigate to this registry path below and delete the “**SusClientID**” and “**SusClientIDValidation**” registry values in the key
HKLM\Software\Microsoft\Windows\CurrentVersion\WindowsUpdate
and restart the windows update service
And perform or run the following from the CLI below
wuauclt /resetauthorization /detectnow
wuauclt.exe /detectnow /reportnow
Links
https://social.technet.microsoft.com/Forums/lync/en-US/c331d314-2f04-4b07-a3fd-878183b8101d/wsus-clients-appear-then-disappear-in-console?forum=winserverwsus
https://community.spiceworks.com/scripts/show/613-cloned-machines-not-reporting-into-wsus-server
https://community.spiceworks.com/how_to/91430-wsus-computers-are-not-showing-up-in-the-console-what-s-wrong
https://blog.netnerds.net/2006/12/wsus-force-registration-of-clients-that-are-not-showing-up/