I have a strange scenario where I have 2 OpenVPN servers on my LAN (192.168.1.0/24) both over TUN. Server A (on 192.168.1.100) provides clients with addresses on the 172.16.0.0/24 subnet and Server B (192.168.1.1) provides clients with the 172.16.10/24 subnet.
Clients on the 2 OpenVPN Servers need to talk to each other. I've applied the following config to Server A:
push "route 172.16.1.0 255.255.255.0 192.168.1.1 1"
The resulting routing table entry for a client on Server A is:
172.16.1/24 192.168.1.1 UGSc 0 2 en0
On server B, I applied the config:
push "route 172.16.0.0 255.255.255.0 192.168.1.100 1"
On both servers, I made sure to allow access to the both the LAN and the other OpenVPN's networks. However, attempting to ping 172.16.1.1 on a client connected to Server A, results in "Network Unreachable." The similar occurs with a client on Server B.
If it is of any additional use, Server B resides on Pfsense. Server A is a virtualized OpenVPN Access Server.