In my local network, an NFS server runs on FreeBSD 11.3. I use FreeBSD
12.1 and KaliLinux as clients. They work well with this server. But I
can not get OpenBSD 6.6 to work. After the attempt to mount the NFS,
OpenBSD 6.6 stops responding to me both through the local console and
over the network through the SSH client. I have to use the power off
button. To eliminate the hardware error, I installed FreeBSD 12.1 on
the same computer as the OpenBSD 6.6 and the NFS client on FreeBSD
12.1 worked well.