Google OpenId: No OpenID endpoint found (intermittent)

Usually using the Google OpenId works fine, thousands of times a day, then it will start intermittently going wrong and timing out for an hours or so (some requests will validate but not all). Repeated validation will eventually work.

Error messages are:

Event code: 200000 
Event message: No OpenID endpoint found. : https://www.google.com/accounts/o8/id 

Sequence contains no elements

Adding in log4net yields:

DotNetOpenAuth.Yadis:
Error while performing discovery on: "https://www.google.com/accounts/o8/id": 
DotNetOpenAuth.Messaging.ProtocolException:
 Error occurred while sending a direct message or getting the response. 
 ---> System.Net.WebException: The operation has timed out     
  at System.Net.HttpWebRequest.GetResponse()    
  at DotNetOpenAuth.Messaging.StandardWebRequestHandler.GetResponse
     (HttpWebRequest request, DirectWebRequestOptions options) 
     in  c:\...\Dot...Core\Messaging\StandardWebRequestHandler.cs:line 127    
 --- End of inner exception stack trace ---     
  at DotNetOpenAuth.Messaging.StandardWebRequestHandler.GetResponse
     (HttpWebRequest request, DirectWebRequestOptions options) 
     in c:\...\Dot...Core\Messaging\StandardWebRequestHandler.cs:line 175
  at DotNetOpenAuth.Messaging.UntrustedWebRequestHandler.GetResponse
     (HttpWebRequest request, DirectWebRequestOptions options)
     in c:\...\Dot...Core\Messaging\UntrustedWebRequestHandler.cs:line 250
  at DotNetOpenAuth.Yadis.Yadis.Request
     (IDirectWebRequestHandler requestHandler,
       Uri uri, Boolean requireSsl, String[] acceptTypes) 
     in c:\...\Dot...OpenId\Yadis\Yadis.cs:line 172
  at DotNetOpenAuth.Yadis.Yadis.Discover
     (IDirectWebRequestHandler requestHandler, UriIdentifier uri, Boolean requireSsl)
     in c:\...\DotNetOpenAuth.OpenId\Yadis\Yadis.cs:line 63
  at DotNetOpenAuth.OpenId.UriDiscoveryService.Discover
     (Identifier identifier, IDirectWebRequestHandler requestHandler,