WSUS - 2012 R2 Clients not reporting

We have a number of severs for different customers that are separated in to different computer groups, these machines are not on a domain although hook in to WSUS with a registry change. Some Machines for customers are reporting fine, however some are not. The Registry settings appear to be the same for all customers, however in the windowsupdate.log file I am getting the following from machines not repoting in to WSUS -

2015-05-27  01:39:48:203     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 1.
2015-05-27  01:42:03:125     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  01:42:03:235     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 3.
2015-05-27  01:43:06:157     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  01:43:06:172     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 1.
2015-05-27  01:44:53:235     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  01:44:53:266     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 3.
2015-05-27  01:45:56:219     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  01:45:56:219     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 1.
2015-05-27  01:48:30:017     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  01:48:30:235     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 3.
2015-05-27  01:49:33:017     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 1.
2015-05-27  01:51:30:908     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  01:51:31:236     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 3.
2015-05-27  01:52:33:908     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  01:52:33:923     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 1.
2015-05-27  01:54:26:798     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  01:54:27:236     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 3.
2015-05-27  01:55:29:846     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  01:55:29:861     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 1.
2015-05-27  01:57:17:221     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  01:57:17:268     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 3.
2015-05-27  01:58:20:299     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  01:58:20:330     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 1.
2015-05-27  02:00:16:612     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  02:00:16:737     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 3.

This is pumped in to the log file over and over but then i see the following -

2015-05-27  01:58:20:330     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 1.
2015-05-27  02:00:16:612     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  02:00:16:737     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 3.
2015-05-27  02:01:19:612     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 1.
2015-05-27  02:02:43:924     828    dfc EP  FATAL: EP: CSLSEndpointProvider::GetWUClientData - failed to get SLS data, error = 0x8024500C
2015-05-27  02:02:43:924     828    dfc EP  FATAL: EP: CSLSEndpointProvider::GetEndpointFromSLS - Failed to get client data, error = 0x8024500C
2015-05-27  02:02:43:924     828    dfc EP  FATAL: Failed to obtain 9482F4B4-E343-43B6-B170-9A65BC822C77 redir Client/Server URL, error = 0x8024500C
2015-05-27  02:02:43:924     828    dfc PT  WARNING: PTError: 0x8024500c
2015-05-27  02:02:43:924     828    dfc PT  WARNING: Initialization failed for Protocol Talker Context: 0x8024500c
2015-05-27  02:02:43:924     828    dfc PT  WARNING: PTError: 0x8024500c
2015-05-27  02:02:43:924     828    dfc EP  FATAL: EP: CSLSEndpointProvider::GetWUClientData - failed to get SLS data, error = 0x8024500C
2015-05-27  02:02:43:924     828    dfc EP  FATAL: EP: CSLSEndpointProvider::GetEndpointFromSLS - Failed to get client data, error = 0x8024500C
2015-05-27  02:02:43:924     828    dfc EP  FATAL: Failed to obtain 9482F4B4-E343-43B6-B170-9A65BC822C77 redir Reporting URL, error = 0x8024500C
2015-05-27  02:02:43:924     828    dfc PT  WARNING: PTError: 0x8024500c
2015-05-27  02:02:43:924     828    dfc Report  FATAL: OpenReportingWebServiceConnection, GetReportingServerUrl failed with error, hr = 0x8024500C.
2015-05-27  02:02:43:924     828    dfc Report  WARNING: HandleEvents, OpenReportingWebServiceConnection, with NULL CallerIdentity failed with error, hr = 0x8024500C.
2015-05-27  02:02:43:924     828    dfc Report  WARNING: Reporter failed to upload events with hr = 8024500c.
2015-05-27  02:03:50:331     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  02:03:50:737     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 3.
2015-05-27  02:04:53:362     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 1.
2015-05-27  02:07:24:441     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 2.
2015-05-27  02:07:24:738     828    cc8 Service UpdateNetworkState Ipv6, cNetworkInterfaces = 3.

I am under strict Change Control for this environment, I would disable ipv6 from the network adapter to see if this makes any difference, but even this can take ours to sort. Can anyone suggest anything why this is happening ?

Reg settings -

reg_settings

reg_settings_1

Removing ipv6 does resolve issues.