@x9rok
It is some while since I last used it, but from what I remember, if there was no task for the PC you should get the FOG menu, which would then time out after the period set in the FOG GUI, if you didn’t select an option.
If you don’t get the FOG menu then it may be that the ipxe script needs changing to pass extra parameters to boot.php.
If the reboot is caused by the timeout expiring, then it could be that the network card is left in a funny state by the previous boot attempt.
As per the comment from george1421, you don’t need to change the boot order, F10 or F12 should get you a boot menu, depending on the BIOS. We used Dell PCs, and it was F12 for them.
You really don’t want usb at the top of the boot order, as if you forget to change it back, it is security hole.
It is worth making your BIOS password protected and only having Hard Disk on the boot device list, that way only authorised people can boot from anything other than the Hard Disk.