I recently turned off IPV6 on my WSUS server and had very strange results.
In the WSUS management console, all computers, the IP address for the WSUS box now showed the IP address as just ::1 and the box would no longer get updates from itself.
Here's a log snippet.
2015-07-02 23:53:20:496 844 bbc EP Got WSUS SimpleTargeting URL: "http://dpwsus02:8530"
2015-07-02 23:53:20:516 844 bbc PT Initializing simple targeting cookie, clientId = 5b3f62e4-2e8b-4978-adf1-8301ab0bcbb3, target group = , DNS name = dpwsus02
2015-07-02 23:53:20:516 844 bbc PT Server URL = http://dpwsus02:8530/SimpleAuthWebService/SimpleAuth.asmx
2015-07-02 23:54:39:579 844 bbc WS WARNING: Nws Failure: errorCode=0x803d0006
2015-07-02 23:54:39:579 844 bbc WS WARNING: Original error code: 0x80072ee2
2015-07-02 23:54:39:579 844 bbc WS WARNING: There was an error communicating with the endpoint at 'http://dpwsus02:8530/ClientWebService/client.asmx'.
2015-07-02 23:54:39:579 844 bbc WS WARNING: There was an error receiving the HTTP reply.
2015-07-02 23:54:39:579 844 bbc WS WARNING: The operation did not complete within the time allotted.
2015-07-02 23:54:39:717 844 bbc WS WARNING: The operation timed out
2015-07-02 23:54:39:717 844 bbc WS WARNING: Web service call failed with hr = 8024401c.
2015-07-02 23:54:39:717 844 bbc WS WARNING: Current service auth scheme='None'.
2015-07-02 23:54:39:717 844 bbc WS WARNING: Proxy List used: '(null)', Bypass List used: '(null)', Last Proxy used: '(null)', Last auth Schemes used: 'None'.
2015-07-02 23:54:39:717 844 bbc WS FATAL: OnCallFailure(hrCall, m_error) failed with hr=0x8024401c
2015-07-02 23:54:39:718 844 bbc PT WARNING: PTError: 0x8024401c
2015-07-02 23:54:39:724 844 bbc PT WARNING: GetCookie_WithRecovery failed : 0x8024401c
2015-07-02 23:54:39:724 844 bbc PT WARNING: RefreshCookie failed: 0x8024401c
2015-07-02 23:54:39:724 844 bbc PT WARNING: RefreshPTState failed: 0x8024401c
2015-07-02 23:54:39:724 844 bbc PT WARNING: Sync of Updates: 0x8024401c
2015-07-02 23:54:39:724 844 bbc PT WARNING: SyncServerUpdatesInternal failed: 0x8024401c
2015-07-02 23:54:39:725 844 bbc Agent * WARNING: Failed to synchronize, error = 0x8024401C
2015-07-02 23:54:39:797 844 bbc Agent * WARNING: Exit code = 0x8024401C
2015-07-02 23:54:39:797 844 bbc Agent *********
2015-07-02 23:54:39:797 844 bbc Agent ** END ** Agent: Finding updates [CallerId = AutomaticUpdatesWuApp]
2015-07-02 23:54:39:798 844 bbc Agent *************
2015-07-02 23:54:39:798 844 bbc Agent WARNING: WU client failed Searching for update with error 0x8024401c
2015-07-02 23:54:39:805 844 470 AU >>## RESUMED ## AU: Search for updates [CallId = {AEE50FEA-6D61-4048-881F-DCF89C100A4E} ServiceId = {3DA21691-E39D-4DA6-8A4B-B43877BCB1B7}]
2015-07-02 23:54:39:805 844 470 AU # WARNING: Search callback failed, result = 0x8024401C
2015-07-02 23:54:39:805 844 470 AU #########
2015-07-02 23:54:39:805 844 470 AU ## END ## AU: Search for updates [CallId = {AEE50FEA-6D61-4048-881F-DCF89C100A4E} ServiceId = {3DA21691-E39D-4DA6-8A4B-B43877BCB1B7}]
2015-07-02 23:54:39:805 844 470 AU #############
2015-07-02 23:54:39:806 844 470 AU All AU searches complete.
2015-07-02 23:54:39:806 844 470 AU # WARNING: Failed to find updates with error code 8024401c
2015-07-02 23:54:39:812 844 470 AU AU setting next detection timeout to 2015-07-03 09:54:39Things I tried include ipconfig /flushdns, waiting several days and trying again, multiple reboots, deleting the WSUS server from its own database and deleting the client registry entries and doing wuauclt /resetauthorization /detectnow. When I reran wuauclt, the server was added again to the management console again with ::1 as the IP address but all the same errors occurred trying to update.
If I restore IPV6 then the updates work for updating itself. Updates continued to work for all other clients throughout.
Any suggestions how to fix this?