Also curious to know if hostname or IP address is used.
Test from master server and media server with ping and bptestbpcd using hostnames.
Extract from NBU Status Code manual:
NetBackup status code: 47
Message: host is unreachable
Explanation: An attempt to connect to another computer failed.
Do the following, as appropriate:
■ Verify that the name service (or services) used by the client are configured to resolve the host names of the NetBackup server correctly.
■ Verify that the name service (or services) used by the server are configured to resolve the host name of the NetBackup client correctly.
■ Try to ping the client from the server and the server from the client.
■ If you continue to have problems, do the following:
See "Resolving network communication problems" in the Troubleshooting Guide.
if hosts files on server(s) or client(s) have been updated or if changes were made to DNS, you need to refresh NBU host cache on servers before attempting backups or connections within one hour of the change.
NBU only refreshes host cache once every hour.