I finally made it work! The case was I needed to boot the undionly.kpxe FIRST to be able to boot from http.
Code:
allow booting;
allow bootp;
#ddns-update-style none;
#log-facility local7;
default-lease-time -1;
max-lease-time 7200;
authoritative;
#option space gpxe;
#option gpxe-encap-opts code 175 = encapsulate gpxe;
#option gpxe.bus-id code 177 = string;
subnet 192.168.1.0 netmask 255.255.255.0 {
use-host-decl-names on;
range 192.168.1.3 192.168.1.254;
option routers 192.168.1.1;
option broadcast-address 192.168.1.255;
option root-path "192.168.1.2:/tftp";
next-server 192.168.1.2;
option domain-name-servers 192.168.1.1;
option domain-name "lab.local";
option bootfile-name "undionly.kpxe"; #This line made it work
#filename "undionly.kpxe";
filename "http://192.168.1.2/boot.php";
#filename "pxelinux.0";
server-name "klonstation";
server-identifier 192.168.1.1;
}