I had the same problem and tried to solve it with the nfs-server.service unit, but did not succeed. So I finally ended up with a workaround and put a script into crontab, like
#crontab -e @reboot /usr/local/bin/exportNFS
and
#cat /usr/local/bin/exportNFS sleep 5 /usr/sbin/exportfs -r
I had the same problem and tried to solve it with the nfs-server.service unit, but did not succeed.
So I finally ended up with a workaround and put a script into crontab, like
#crontab -e bin/exportNFS
@reboot /usr/local/
and
#cat /usr/local/ bin/exportNFS sbin/exportfs -r
sleep 5
/usr/