Ensure the boot image is redistributed to all relevant Distribution Points (DPs). :

If your environment uses HTTPS/Enhanced HTTP, an untrusted or missing certificate will block the download.

Over time, configuration settings in SCCM can drift or become corrupted.

: Issues with the "Enable PXE responder without Windows Deployment Service" setting on the Distribution Point. Stack Overflow Troubleshooting & Resolution Steps

On modern fiber, those settings fly. But this building was old. The copper in the walls was legacy, prone to tiny packet drops that a standard browser wouldn't notice, but a TFTP handshake would find fatal. Elias dialed the settings back: Window Size: Block Size: He restarted the Windows Deployment Services (WDS)

“No,” Tomás whispered. “No more.”