GRT Backup is not supported for a remote server which is accessible to media server using a NAT setup

Problem

A Granular Restore Technology (GRT) enabled backup job targeted to disk fails with error "0xe00084f9 - A communications failure has occurred between the Backup Exec job engine and the remote agent".

V-79-57344-65072 - The connection to target system has been lost. Backup set canceled.

Error Message

Backup Job Log:

V-79-57344-65072 - The connection to target system has been lost. Backup set canceled.
Final error: 0xe000fe30 - A communications failure has occurred.

An error occurred while connecting to the Backup Exec Remote Agent on the media server. Ensure that the job options are correct, and then submit the job again. The backup set was not created.

The Sharepoint resource is not responding. Backup set canceled. 

The Backup Exec job engine debug log reports the following error if the job is run with debugging enabled:

ERROR: 17 Error: Cannot connect / not connected
PDIBackupBSDProcessor::EstablishPDIDataConnection() - dataConnect failed with error code : 0x00000017
PDIBackupBSDProcessor::ProcessBSD( ) - Could not connect PDI Source(EXCHANGE2003) to the PDI store(BE11)
 

Cause

The above error occurs while running a GRT enabled backup job to disk of a remote server that is accessible to the Backup Exec server over a NAT (Network Address Translation) setup.  

Solution

Non-GRT Backup should work. GRT Backup is not supported when a remote server is talking to the media server using Network Address Transalation (NAT).