SMSPXE.log showed the MP generating the policy successfully, but the client never received it. Network traces revealed that an intermediate switch had HTTP Intercept enabled (a feature for web filtering). This switch was intercepting the client's HTTP GET request for variables.dat and returning a cached "404 Not Found" page intended for a different web server.
SCCM uses PXE to deploy operating systems to computers. When a computer is configured to boot from the network, it contacts the SCCM server to request a boot image. The SCCM server then provides the computer with a boot image, which includes the necessary files to complete the installation. unable to download pxe variable file. exit code 14 sccm
If you have a mixed environment (WDS and SCCM PXE), there can be a conflict. SMSPXE
While the error code suggests a download failure, the root causes generally fall into three distinct categories: Authentication and Certificates, Network Communication (Firewalls and Ports), and Configuration Drift. SCCM uses PXE to deploy operating systems to computers
The variable file is typically downloaded over SMB (TCP 445) or HTTP/HTTPS (TCP 80/443) from the DP or MP. If your network team filters inter-VLAN traffic, the initial PXE boot (UDP 67,68,69) may succeed, but the subsequent file download fails.