The server denied anonymous access to the client. Client Name: %4 Client Address: %2 Session ID: %5 Guidance: You should ...

The server denied anonymous access to the client.

Client Name: %4
 Client Address: %2
Session ID: %5

Guidance:

You should expect this error when a client attempts to connect to shares and does not provide any credentials. This indicates that the client is not providing a user name (and domain credentials, if necessary). By default, Windows Server denies anonymous access to shares.

This error does not always indicate a problem with authorization, but mainly authentication. It is more common with non-Windows clients.