In case you have PXE Boot working normally but suddenly it is not working anymore, it may be because of the WDS service. This might sound strange but sometimes Windows Deployment Services (WDS) Server does not start after restarting the server, even if it is set to automatically start. It happened to me a few times….

Starting the service fixed the problem (in my case) every time. I didn’t tried, but maybe configuring delayed start for this service will fix the problem in the future.