Autosys version 11.3.6 SP5 with cumulative fix 1.
When the agent is back online, AutoSys registers itself with the agent and sends the hostname name to use.
Autosys uses the gethostname() O/S API to get the hostname.
This means that, when the agent was back online, autosys collected on the machine the hostname "xxxxxxx" which is defined somewhere on the Autosys server machine.
To workaround that and be sure to always you the FQDN, you can uncomment the ManagerHostAlias value in the config.AUTOSERV, and specify the FQDN. Otherwise, you would need to work with your sysadmins to ensure that the hostname returns the FQDN on the server (as it likely did before the network problem you got).