Cannot create a backup copy on a secure storage server. Failed to transfer backup to secure storage (4381171)

The below mentioned error message is displayed when the backup agent on a DC fails to transfer the backup to the Secure Storage server

• Cannot create a backup copy on a secure storage server. Failed to transfer backup to secure storage

The configuration may be something as mentioned below.

1. The Secure Storage in the RMAD console is configured with the computer name of the Secure Storage server
2. The computer collection is setup to store backup on a remote storage with the correct credentials
3. Secondary Storage is enabled to store the backup on the Secure Storage server i.e., computer name of the Secure Storage server is selected

The issue might appear to be a TLS handshake failure between the DC and the Secure Storage Server(despite the same certificates working successfully for the RMAD Console -> Secure Storage Server communication).

The outgoing traffic might have been blocked from DC to Secure Storage Server on port 48001. 

The below mentioned steps will resolve the issue.

1. Re-add the Secure Storage server into RMAD using IP Address instead of hostname (this will downgrade handshakes from forcing Kerberos hostname, to NTML ipv4 address)
2. Re-deploy the agent to the domain controller
3. Reboot DC
4. Reboot RMAD

If the outgoing traffic is blocked from DC to Secure Storage Server on port 48001, make an exception to that port.