You may have special port requirements for Backup Exec if you use a firewall. Firewalls sometimes affect system communications between a media server and remote systems that reside outside the firewall environment.
When Backup Exec is not running operations, it listens to ports for incoming communication from other services and agents. Backup Exec initially communicates with the Remote Agent using a static listening port to begin an operation. The agent and the media server then use dynamic ports to pass data back and forth.
Table: Backup Exec Listening Ports