Hi @Krish004 , hope all is well!
A Network Gateway is what you described:
You set up a client to act as the connection for clients on one side of gateway to talk to the other side. Copying this text from the link below here:
The Commvault network gateway is a special configuration in which a dedicated Commvault agent is placed in a perimeter network that is configured to allow connections (from inside and outside networks) into the perimeter network. The network gateway (the agent running in the perimeter network) authenticates, encrypts, and allows the tunnel connections it accepts to connect the clients operating outside of the private network to clients operating inside of it. The Commvault network gateway supports NAT operations.
The Commvault network gateway acts like a Private Branch Exchange (PBX) that sets up secure conferences between dial-in client calls. With this setup, network routes can be configured to disallow straight connections between inside and outside networks.
https://documentation.commvault.com/11.24/expert/7270_network_gateway_in_perimeter_network.html
In your example, you configured a Data Interface Pair for the VLAN, so was that for the interface on the gateway to the Backup VLAN or the Storage VLAN? The SQL server shouldn’t need a DIP for the Storage side because it is talking to the backup network side (I’m assuming the clients connect on the Backup network, but not the storage network, and the Gateway connects to both Backup and Storage VLANs).
I would need to see more about what was failing (log file messages) and then see the same logs when it worked to see exactly what happened, and a diagram of the setup would help greatly to ascertain anything more.
Then we can really break this down