I was developing an operating system deployment for a customer using Config Mgr 2012. I had successfully carried out all previous work and was commencing the testing of my task sequence. I pressed F12 for network boot and the device booted into PE. However as it was "Preparing network connections" it rebooted without warning and the task sequence failed.
I was very confident that all my configuration was correct and I tried once again with the same result. At this stage I tried a different device. Again the result was the same.
No issues were found in the log files and STP Portfast was enabled on the switch port. However when I was checking the port configuration I noticed that there were excessive errors associated with that port. It looks like the internal cabling was faulty and showed intermittent failures on testing.
After connecting to a different port I was able to test my task sequence successfully.