08091 Detail for 8017: The user is attempting to logon from a non-authorized host. %s
Logon restriction by host has been enabled and the user is attempting to logon from a host that they are not authorized to use. Error 8017 was returned in the logon response message.
Investigate why an account is attempting to logon from a host it is not authorized to use, and either remove the IP address restriction if the logon should have been allowed, or deal with it appropriately if the attempt was accidental or malicious.