Service Bus ACS Token Random Errors -- Unable to connect to the remote server / The operation has timed out /

Hi,

Sending notifications using Azure Service bus notification hub, which was worked fine, since last week.

From Aug 11th, randomly getting different Errors about 80%, while trying to get ACS Auth Token with HTTP
https://<ns>.servicebus.windows.net-sb.accesscontrol.windows.net/WRAPv0.9/

Random Error messages at different times:

1 ) Unable to connect to the remote server
2) The underlying connection was closed
3) The operation has timed out
4) The remote server returned an error: (401) Unauthorized

Also, it works fine with proper access token, randomly, about 20%.
Any help could be appreciated, to resolve the issue

Regards,
Dev