First, make sure the BIOS is up to date.

Second, make sure the BIOS Settings are in place, I took this from a dell forum about the latitude 7275 (unfortunately, I don't remember the URL).
I would recommend trying these settings, or check the device Manual and attempt to mirror those, if the BIOS is not able to offer the dongle as a boot option, it will not PXE boot to the KACE Appliance.:




Also, the driver pack for WinPE 10 version A13 , is the only one that contains drivers for that mode, DELL released this version on June 19th, 2019, that means ANY KBE (boot environment), created before that date, will fail to work properly with that hardware.

https://www.dell.com/support/home/my/en/mybsd1/drivers/driversdetails?driverid=r2w7m

You will need to extract the CAB file with 7zip, and replace the drivers in \\KACE-IP\drivers\kbe_windows_x64\  folder, recache all drivers and build a new KBE.

But first you will need to troubleshoot the BIOS.

When you have laptops or tablets that do not have a NIC then you use a USB to NIC  adapter  then a USB bootable  made from the k200 boot enviroment.

Boot Environment Detail