Hello Raymond Baj,
First look at logs in ZD at the time of lock-up, this will tell why it is happening and take corrective action based on that.
Make sure Honeywell 99GX barcoders drivers are up-to date.
Try using 802.11a on the device, things would get better if it is interference related.
Lockup usually happens because of below situations:
If AP is changing channels then at times they fail to reconnect back to AP. Just check logs on ZD GUI and if you find that AP is changing channel then fix the channel on the AP for a quick test.
it could be encryption related primarily due to rekeying not being handled correctly by either devices so start with open SSID with no ecryption. If no lock up seen then go to next level security option and test.
hope this helps.