Hello,
It doesn't seem to be a hardware problem, rather as the error mentions, the media server is probably not able to establish a connection with the remote servers during backup. Are you able to ping the remote servers from the backup exec server and vice versa? Do you have the firewall enabled on the remote servers?
Regarding the Xp machines with SP 2, refer to the following technote:
Backups fail with "A communications failure occurred on the backup device" when trying to back up remote computers with Backup Exec on a computer running Windows XP Service Pack 2 firewall.
http://support.veritas.com/docs/274793
Check if that helps. If the issue still persists, do write back to the forum.
If we do not receive your update within two business days, this post would be marked ‘assumed answered’ and would be moved to ‘answered questions’ pool.
Regards.
