I have WSUS server running on 2012 R2.  I made sure to update the server with all patches before adding the WSUS role.  The WSUS service works great for a few minutes and then crashes.  Clients are able to pull and update themselves for a few minutes before the crash.

I have attached the error below:

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The WSUS administration console was unable to connect to the WSUS Server via the remote API.

Verify that the Update Services service, IIS and SQL are running on the server. If the problem persists, try restarting IIS, SQL, and the Update Services Service.

System.Net.WebException -- The request failed with HTTP status 503: Service Unavailable.

Source
System.Web.Services

Stack Trace:
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
   at Microsoft.UpdateServices.Internal.ApiRemoting.ExecuteSPGetConfiguration()
   at Microsoft.UpdateServices.Internal.DatabaseAccess.AdminDataAccessProxy.ExecuteSPGetConfiguration()
   at Microsoft.UpdateServices.Internal.BaseApi.UpdateServerConfiguration.Load()
   at Microsoft.UpdateServices.Internal.ClassFactory.CreateWellKnownType(Type type, Object[] args)
   at Microsoft.UpdateServices.Internal.ClassFactory.CreateInstance(Type type, Object[] args)
   at Microsoft.UpdateServices.Internal.BaseApi.UpdateServer.GetConfiguration()
   at Microsoft.UpdateServices.UI.AdminApiAccess.CachedUpdateServerConfiguration.GetFreshObjectForCache()
   at Microsoft.UpdateServices.UI.AdminApiAccess.CachedObject.RefreshCache()
   at Microsoft.UpdateServices.UI.AdminApiAccess.CachedObject.GetFromCache()
   at Microsoft.UpdateServices.UI.AdminApiAccess.PermissionsManager.IsPermitted(UserOperation operation)
   at Microsoft.UpdateServices.UI.SnapIn.Scope.UpdatesSummaryScopeNode.RefreshPermissions()
   at Microsoft.UpdateServices.UI.SnapIn.Scope.ServerSummaryScopeNode.AddChildNodes()
   at Microsoft.UpdateServices.UI.SnapIn.Scope.ServerSummaryScopeNode.ConnectToServerAndPopulateNode(Boolean connectingServerToConsole)
   at Microsoft.UpdateServices.UI.SnapIn.Scope.ServerSummaryScopeNode.ResetScopeNode()

Hi,

As the log has mentioned, have you tried to restart the IIS, SQL, and the Update Services Service?

Have you configured the SSL? If yes, we need to connect to the WSUS with SSL.

Have you checked the RAM utilization? When the RAM is exhausted, this issue may occur.

Besides, have you configured other website on the WSUS server?

Best Regards.