Alright, so OpenBSD won't reply to requests from ports below 1024 or the NFS port.
The issue is in OpenBSD (inetd) and not in NetBSD. Their implementation is not
compatible with any other and it's not documented either.

I don't see a good and clean way to work around this in NetBSD. One option would
be a command-line parameter to use an unprivileged port. This would still fail
in a mixed environment. Another is to use two sockets and send everything twice.
Or NetBSD could behave as OpenBSD and break interoperability with itself and
any other implementation.

I think their "fix" is pretty half-assed, so I wouldn't follow that route.

-- 
Christian