You shouldn't need to do that. Is it your ZD that's crashing? Your APs should keep trying to reconnect for at least 30 minutes before they reboot and go into recovery mode. You should use a DHCP option 43 or DNS 'zonedirector.local.domain' with your ZD's IP to direct your APs too. I think I would still recommend upgrading to 9.4.3 and to monitor your network traffic for peak periods, and see if they correspond to your ZD/AP problems.