Why do I need to manually start OVPN clients in a specific order?

[McMurphy]

I have three OpenVPN clients on my pfSense connecting to the same service (CloudConnexa). Each has a unique interface and subnet pushed from the server:

• Client1 - 10.27.0.0/24 - ovpnc7
• Client2 - 10.27.10.0/27 - ovpnc9
• Client3 - 10.27.40.0/27 - ovpnc10

The routes can only be accessed if the OVPN clients are started in a specific sequence

• Client2 - 1st
• Client3 - 2nd
• Client1 - 3rd

If the clients are started in a different sequence the interface sometimes adopts it's predecessor's interface. For example:

If Client1 is started followed by Client2 then Client2 adopts the interface value of Client1

If Client1 is started followed by Client3 then Client3 adopts the interface value of Client1

If Client3 is started followed by Client1 then everything works correctly

The matrix below shows the different combinations of the three:

I am really stuck here!