Recently on adding some machines and updates to a existing WSUS server that had been stable for a whole year, I was getting the server being unresponsive , and the reset server node would not work

After restarting the Windows Update Server Service , the error below would display in the event log : 

The WSUS content directory is not accessible. System.Net.WebException: The remote server returned an error: (503) Server Unavailable. at System.Net.HttpWebRequest.GetResponse() at Microsoft.UpdateServices.Internal.HealthMonitoring.HmtWebServices.CheckContentDirWebAccess(EventLoggingType type, HealthEventLogger logger)

Running IISRest in the Command prompt brought the site back online  , however clearly this was a workaround to teh crash , Turns out you need some tweaking of the Website in IIS to stop this!

1. On your WSUS Server, launch the IIS Manager
2. Open Application Pools
3. Right click ‘WsusPool’ and select ‘Advanced Settings…’
4. To support the maximum SCCM Software Update Point clients, change ‘Queue Length’ from the default 1,000 to 25,000
   
5. If your server is NUMA aware, change ‘Maximum Worker Processes’ from the default 1 to 0. If you don’t know if your server is NUMA aware, leave this value default
   
6. Change ‘”Service Unavailable” Response Type’ from the default HttpLevel to TcpLevel
7. Change ‘Failure Interval (minutes) from the default 5 to 30
8. Change ‘Maximum Failures’ from the default 5 to 60
   
9. Click ‘OK’ to save the App Pool changes
10. From an administrative command prompt, type IISRESET

This is also a good Cleanup script to schedule :