I too have the very same problem where Windows PE is "Preparing Network Connections" then the laptop reboots with no error log afterwards.
I can F8 into command prompt prior to the reboot and run ipconfig and I can confirm that I'm able to see my network, so I know it's not a NIC driver issue, the correct NIC driver is injected into the boot.wim which is Intel 82567LM.
I'm suspecting it's something to do with security permissions preventing my access into the source folder where I have my operating system image stored to be deployed onto the laptop.
I have made sure all permissions are set correctly.
Any help in solving this would be appreciated.
Cheers