While setting up a new OpenVPN, I got this message:

Sep 23 21:05:25 ascalon openvpn[18770]: krynn/aaa.bbb.ccc.ddd:xxxxx IP packet with unknown IP version=3 seen

The cause was that I had set my OpenVPN server to “dev tun”, while setting my Windows client to “dev tap” in the configuration. Changing the client to also be “dev tun” fixed the issue.