When we see "WLAN -Not Installed" on the display, it means that the printer doesn't have the WiFi module. We can verify that by issuing the following SGD command.
! U1 getvar "wlan.mac_addr"
If "00:00:00:00:00:00" is returned from the above command, it tells us that there is no mac address of a WiFi module, which can further confirms that there is no WiFi module installed on the printer. If a valid mac address is returned by the above SGD command while we still see "WLAN -Not Installed" on the display, then there could be a hardware issue. In the case of hardware issue, we should contact the Zebra Tech Support.