What is this error ? Unable to authenticate Remote domain is not accessible according to our configuration

Hi I getting this error in the logs

2016.07.08 17:31:19 org.jivesoftware.openfire.session.LocalOutgoingServerSession[Authenticate local domain: ‘myddns.ddns.net’ to remote domain: ‘192.168.1.99’] - Unable to authenticate: Remote domain is not accessible according to our configuration (typical causes: server federation is disabled, or domain is blacklisted).

Any ideas?