WSUS can not sync, error in ipv6 address

Hello everyone, 
While I installed wsus in my Windows 2012 R2 server, and start sync, the server report an error like this:

WebException: 无法连接到远程服务器 ---> System.Net.Sockets.SocketException: 向一个无法连接的网络尝试了一个套接字操作。 [2a01:111:f330:1790::a01]:443
在 System.Net.HttpWebRequest.GetRequestStream(TransportContext& context)在 System.Net.HttpWebRequest.GetRequestStream()
   在 System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
   在 Microsoft.UpdateServices.ServerSyncWebServices.ServerSync.ServerSyncProxy.GetAuthConfig()
   在 Microsoft.UpdateServices.ServerSync.ServerSyncLib.InternetGetServerAuthConfig(ServerSyncProxy proxy, WebServiceCommunicationHelper webServiceHelper)
   在 Microsoft.UpdateServices.ServerSync.ServerSyncLib.Authenticate(AuthorizationManager authorizationManager, Boolean checkExpiration, ServerSyncProxy proxy, Cookie cookie, WebServiceCommunicationHelper webServiceHelper)
   在 Microsoft.UpdateServices.ServerSync.CatalogSyncAgentCore.SyncConfigUpdatesFromUSS()
   在 Microsoft.UpdateServices.ServerSync.CatalogSyncAgentCore.ExecuteSyncProtocol(Boolean allowRedirect)

My server can only support ipv4, so I think while wsus using ipv6, I can not sync.

But how can I disable ipv6 sync? I have already disbale ipv6 in my network connections.

Thanks.