Single Primary Site running SCCM 2012 R2 on 2012 R2 server.
WSUS: 8530/8531
WCM.Log
System.Net.WebException: The request failed with HTTP status 503: Service Unavailable.~~ at Microsoft.UpdateServices.Administration.AdminProxy.CreateUpdateServer(Object[] args)~~ at Microsoft.SystemsManagementServer.WSUS.WSUSServer.ConnectToWSUSServer(String ServerName, Boolean UseSSL, Int32 PortNumber) SMS_WSUS_CONFIGURATION_MANAGER 6/18/2014 3:25:56 PM 4452 (0x1164)
Remote configuration failed on WSUS Server. SMS_WSUS_CONFIGURATION_MANAGER 6/18/2014 3:25:56 PM 4452 (0x1164)