Blocking Non-VPN Traffic

[RedLeader]

I have 2 physical interfaces on the pfSense box.

192.168.5.1 is the LAN
192.168.4.1 is the WIFI

I also have an OpenVPN Interface that has all WIFI traffic routed through it. In essense, all WIFI is VPN traffic and all LAN is straight to WAN traffic.

I'm trying to find the easiest way to block WIFI/VPN traffic if the VPN goes down or can't connect. I initially tried tagging WIFI traffic and making a block rule off that, and then I tried blocking all traffic with 'WIFI net' in the destination. Neither succeed. What is the right way to do this?

Thanks in advance