/etc/ppp/ip-up file is not being called upon VPN creation; Monterey

I'm trying to add certain subnets to my route table after launching an IKEv2 VPN tunnel from my Mac. I understand that this behaviour can be achieved by placing an executable ip-up file in /etc/ppp/ folder. File perms are correct it has 0755 and root is the owner, however upon firing up the VPN tunnel the route is not being added. I suspect the file is not being called? Contents of the ip-up file: #!/bin/sh /sbin/route add -net 192.168.66.0/24 -interface $1 I'm running Monterey 12.2.1