Comment by sjmulder

I meant to replace it with IP forwarding from a secondary IPv4 address on another host running OpenBSD, but I haven't been able to get that to work yet. Perhaps any OpenBSD/pf folk here have an idea? This is my config (where in the real file the variables are literals):

  pass in on egress inet to $secondary_ipv4 \
    af-to inet6 from $ipv6 to 2a02:a45f:8eaa::2/128

All I get is timeouts and traceroutes with infinite hops. First I tried rdr-to, but that complains of the address family mismatch.