Make sure host can forward the packets

THE PACKETS!

sysctl net.inet.ip.forwarding=1
sysctl net.inet6.ip6.forwarding=1

Enable and start vmd

rcctl enable vmd
rcctl start vmd

Create a disk

vmctl create -s 5G /data2/VM/openbsd0.img

Start the install

vmctl start -c -b /bsd.rd -m 512M -i 1 -n uplink -d /data2/VM/openbsd0.img openbsd0