Linux Mint PXE boot with preseed, cant get it to work

[nzbtuxnews]

Hello,

I made a small ipxe menu that successfully boots a live Mint ISO and it works flawlessly. Now I'd like to have an unattended deployment via preseed. I looked at the example on this Git repo but its structured differently than my menu (maybe why mine doesnt work!??). Gemini has been useless so far as it keeps changing back & forth the parameters and I end up either with a PXE boot that doesnt work (root FS not mounted), squashfs not retrieved and mounted, etc.

The best I could come up with is this menu which, as I said, works perfectly to load the live ISO and dump me to the Desktop (as if I was running it from a USB thumbdrive).

#!ipxe

# --- Global Variables ---
set pxeserver http://support.mydomain:8081
set ub_path ${pxeserver}/ubuntu-squash

# --- Version/Release Paths ---
set rel_m21      /releases/download/21-48716442

# --- Config/Script Paths ---
set usr_ent_pre  ${pxeserver}/preseeds/usr/ent/usr_ent.preseed

:start
menu Unified OS Installer
item --gap -- USR - ENT OPERATING SYSTEM
item usr_ent_os1    Linux Mint 21 XFCE
item --gap -- -----------------------------------------------------------
item custom_exit Return to main menu
choose target && goto ${target}

# --- Boot block ---

:usr_ent_os1
imgfree
sleep 1
set baseurl ${ub_path}${rel_m21}
kernel ${baseurl}/vmlinuz initrd=initrd boot=casper netboot=url url=${baseurl}/filesystem.squashfs -- preseed/url=${usr_ent_pre} auto=true priority=critical automatic-ubiquity only-ubiquity noprompt ip=dhcp
initrd ${baseurl}/initrd
boot

:custom_exit
exit

With this block, the preseed is ignored because its path (URL) is parsed as "http://preseed/url" and I am brought to the desktop however its in install mode (Install as superuser)...

done.
touch: /root/var/crash/crash.init: No such file or directory
rm: can't remove '/root/var/crash/crash.init': No such file or directory
done.
Begin: Creating debconf-communicate 0fo mechanism ... done.
Begin: Running /scripts/casper-bottom ... Begin: Moving mount points... ... mount: mounting /cdrom on /root/cdrom failed: Invalid argument
done.
Begin: Con0guring fstab... ... done.
Begin: Setting up swap... ... done.
Begin: Setting up locales... ...done.
Begin: Setting up automatic login ... ...done.
Begin: Disabling systemd's GPT auto generator... ... done.
Begin: Setting hostname... . done.
Begin: Setting up console keyboard... ... done.
Begin: Applying desktop settings... ...done.
Begin: Regenerating SSL certicate... ...done.
Begin: Loading preseed file... ... chroot: can't change root directory to '/casper/root.squashfs': No such file or directory
--2026-08-27 15:22:44-- http://preseed/url=http://support.mydomain:8081/preseeds/usr/ent/usr_ent.preseed
Resolving preseed (preseed)... failed: Name or service not known.
wget: unable to resolve host address 'preseed'
grep: /root/tmp/usr_ent.preseed: No such file or directory
grep: /root/casper/root.squashfs: No such file or directory
done.

I tried using "url=${usr_ent_pre}" its even worst the OS cant even boot as if its trying to wget the preseed as the squashfs and I end up with BusyBox rescue shell....

Anybody can help me get over this issue? Sure I can be that far but again I tried pretty much everything and documentation on the web is very sparse....