@Hojjati I’ve found a solution for this issue that worked for me.
You need to manually edit the Windows hosts file at C:\Windows\System32\drivers\etc\hosts and add an entry with your FOG server’s IP address followed by the name “fogserver”.

This is necessary because SmartInstaller.exe performs a pinning process during installation, if you notice the installer hangs or fails exactly at that pinning stage, it is definitely due to this resolution issue.

Adding the entry ensures the installer recognizes the server and can download the certificate properly.

I’ve solved this “Invalid security token” error before with two methods.

This error usually happens because the security trust between the node and the server is broken or the encryption keys don’t match.
First, try deleting the host from the FOG Web UI, then perform a Quick Registration on the client machine and run the install again, this resets the trust relationship from scratch.

If the token.dat is still missing after that, open services.msc, manually start the FOGService, and reboot the computer. Manually triggering the service often forces the client to check in and finally generate the missing token.dat file.

@nicolas-moraes I managed to solve it and in my case it was not a FOG or network issue. I verified that DHCP was working correctly (confirmed with tcpdump), options 66/67 were unchanged, TFTP was running, and the FOG web/ipxe boot.php were reachable.

The key test was that when the client stayed at “Start PXE over IPv4”, the FOG server was not receiving any DHCP or TFTP requests at all, which pointed to a client-side problem. Even though Secure Boot and Fast Boot were already disabled, the issue was caused by the BIOS state.

After restoring BIOS defaults on the HP laptop and re-enabling PXE IPv4 boot, everything started working again. It seems some UEFI/PXE flags were stuck, and resetting the BIOS fixed it.