I'm trying to use ProtonVPN to set up split tunneling so that my tun0 is the only network device that is protected by ProtonVPN. I need this because I have file & web servers running on this Linux box (Ubuntu).

With previous VPNs I've used, I would use OpenVPN and add to the openvpn config and this work the way I intended:

    
route-nopull
route 10.0.0.0 255.0.0.0

  

With other VPNs I'd just run

    
curl --interface tun0 ip.me

  

And that would return a VPN ip address.

For some reason, ProtonVPN seems to be blocking me from using the same workflow. Is there a working guide for ProtonVPN to do what I'm trying to do?