I see you have opened a ticket with Vivek, who suggested 22.214.171.124.15 firmware
upgrade. Scanners using an AS400 server system, like VoIP or telnet based
applications, are very time sensitive, and do not work well with dropped packets.
We typically advise using WPA2-PSK (AES, not auto), high priority on the WLAN,
use a dedicated VLAN, and perhaps tunnel the WLAN traffic if the AS400 is
located with your ZoneDirector. You will need to find clean air/low interference
channels. 5G has typically less interference, if the scanners can use 5G. Else
analyze the AP support info files to determine if the AP sees a lot of interference,
(Histogram under Athstats), or the scanner client is perhaps near to a source of
interference on the floor (reported as PER in client stats).