First, to force WSUS clients to re-register with the server, we have mentioned the steps above. You will have to launch the Windows PC and open an elevated Command Prompt. Then you will have to run the command: wuauclt /resetauthorization /detectnow. This command resets the client's authorization settings and initiates a detection cycle. Secondly, after running the command. Wait for a few minutes, and then check the WSUS console to see if the client reappears. If the client still doesn't appear. Ensure that the Group Policy settings are correctly configured, and investigate network or firewall issues.