> While doing this I noticed my old rules referenced lo as the loopback IF, but it's clearly called lo0. You were using interface groups. The loopback interfac

> While doing this I noticed my old rules referenced lo as the loopback IF, but it's clearly called lo0. You were using interface groups. The loopback interface, lo0 is a part of the lo interface group. https://man.openbsd.org/ifconfig#group https://man.openbsd.org/ifconfig#group When upgrading avoid long jumps, and always read the upgrade guides, they cover important changes between releases.