We can only hope that you do not wait another 4 weeks to reply....
Seeing that this is a remote location, can you check if firewall ports are open?
NetBackup Network Ports Reference Guide
NetBackup must connect to TCP port 443 to access the vCenter server. NetBackup
can connect to the vCenter server only through this port for information such as the
VM discovery requests, snapshot creation and deletion, and so on.
The backup host must also connect to the TCP port 902 on the ESX/ESXi hosts.
In specific cases, the backup host must also connect to the TCP port 902 on the
ESX/ESXi hosts.