@newlined I would suggest shorter lease times. Something like below. These values are in seconds, so you can play with them yourself.

default-lease-time 1800; max-lease-time 3600;

After each of these changes, you need to restart dhcp with this command: systemctl restart dhcpd

@newlined you can fix this Behavior if you remove the /var/www/fog and then do: sudo ln -s /var/www/html/fog /var/www/fog

Please mark this as solved.

I was replacing the Kernel here /var/www/fog/service/ipxe and it was suppose to be here /var/www/html/fog/service/ipxe.

Kernel 4.15.2 works if it’s installed in the right place. Sorry for wasting your time.