The problem is with the OpenVPN client running on the Turris Omnia, I"m not running a VPN server.
I’ve created an “unmanaged” network interface named “VPN” covering “tun0”.
I’ve created a firewall zone which accepts input/output/forward/masquarde and allows forward from LAN to VPN and VPN to LAN.
I’m able to start VPN instances using the web ui but traffic through the router doesn’t use the VPN.
This was working fine prior to the upgrade to 3.8* (I had skipped 3.8.0).