Need to discover network for network monitoring tool on VM

We have a network in the 192.168.20.X range that we are trying to discover on our opmanager. They are all cisco devices.

Our NMS (opmanager) is on a VM in the 10.1.1.X network.

We tried to plug a switch from the 192.168.20.X network to our firewall. It is an access port with VLAN 20.

Still unable to ping my 192.168.20.X network.

Should i do an IP route from our core to our firewall? Not really sure how I can reach this. What if I trunked a port on a switch in the 192.168.20.X network, to our sonicwall. Will I be able to see the 10.1.1 network through the trunk

TOPOLOGY https://postimg.cc/p5twqn98