FAQ:I'm seeing "Request to AMANDA CLIENT failed: timeout waiting for ACK"
From The Open Source Backup Wiki (Amanda, MySQL Backup, BackupPC)
This is a common error with the BSD-style Amanda authentications. These authentications are difficult to configure and offer minimal security. If possible, consider using "local" auth (which only works for the local host, and is only available in Amanda-2.6.0 and later) or "ssh" auth. See amanda-auth(7) for details.
If this is not possible, see the corresponding troubleshooting article, planner: ERROR Request to AMANDA CLIENT failed: timeout waiting for ACK.