I set up a VPN gateway in Azure, and configured a P2S connection that connects an on-prem server to the gateway. The Azure P2S configuration asks for an IP pool to assign to the endpoints when they connect, it's set to 172.16.17.0/24.
When the on-prem server successfully connects, it's assigned an IP 172.16.17.2 as expected. It can reach my private subnets on the Azure side normally across the VPN.
However, the on-prem server has its own private IP, 192.168.2.110. From the Azure side, the VMs connected to the VPN gateway can only reach the on-prem server via 172.16.17.2. I need them to be able to reach 192.168.2.110 as well.
I took a look at the effective routing table in Azure. They auto added 172.16.17.0/24 to be routed via the VPN of course. But they have other private IP blocks that are not part of my Vnet address space/subnets set to Drop, including 192.168.0.0/16.
I can't seem to figure out how to add a custom route to my vNic that routes 192.168.2.110 through the same VPN gateway so my VMs can access the on-prem server via this IP.
I tried creating a Routing Table instance, and it allows me to add a route for 192.168.2.110/32, under the "Next Hop Type" I can choose Virtual Network Gateway, but it won't let me specify the IP address of the gateway, and the rule does not seem to work. The auto-added route for 172.16.17.0/24 does have Virtual Network Gateway as hope type and it has the gateway's IP.
Your advice would be greatly appreciated.