The GUID looked wrong. He double-checked the MAC address in the database. Different GUID. Not wrong— old . The device had been imported into SCCM twice. Two GUIDs, one MAC. The PXE request was coming in on the stale GUID, and the MP was looking for a variable file that didn’t exist under that key.
In practical terms, the client is saying: unable to download pxe variable file. exit code 14 sccm
Run ipconfig to see if the device has a valid IP address. If it shows 0.0.0.0 or no adapter, you are missing in your boot image. The GUID looked wrong