On a multihomed (multiple NIC) NAS device, a Repository can be created and backed-up to to a share bound to one network interface, while another share bound to another NIC can have the Repository created, but not written to during a vRanger backup. The NAS device itself is a single piece of hardware, and the VMWare version is ESX (doing direct-to-target Service Console backups).
The vRanger machine can reach the first NIC without problems, and will use this to create the Repository and write the initial master index file. The backups themselves however are coming from the Service Console network on the HOST machines, not the vRanger machine (i.e. in this scenario, the hosts perform the actual backup, and write the data directly to NAS. vRanger resolves the DNS name/IP of this Service Console Network, so if the secondary NIC bound to the second share on the NAS device is not on the Repository IP address that vRanger sees it/resolves it on (or it's VLANd to a different network, etc), the host will not communicate with the secondary share, and the backups jobs to it will fail.
1) Move the Second NIC on the NAS device to the SAME network segment /VLAN as the Service Console of the ESX Host(s). This will allow the hosts' Service Consoles to connect to the second Repository Share and write the backup.
2) OR, through network manipulation/static routes/hosts files on the Ranger machine and/or ESX Hosts (it depends on the environment), create a secondary Service Console (with its own NIC bound to it/separate vSwitch) on the secondary VLAN, and make sure that service console can communicate to the second NIC on the NAS device (connect via an SSH client session (like Putty) to this secondary Service Console, and try a "ping" command to the secondary NIC on the NAS. Also make sure that you give this second NIC on the NAS as different hostname than the primary NIC (otherwise, Ranger will simply resolve the first IP it "sees", which is the primary). If this is not possible to do on your particular NAS device, you must use option #1 above.