Fails to pxe boot ubuntu 20.04 or 22.04 with filesystem.squashfs

[thisisdhanushd3]

[Yes]: This bug persists when memory is increased beyond 8GB.

Describe the bug

Using the exact ipxe script as described for ubuntu netboot

ipxe script
:20.04-boot
imgfree
kernel ${boot_server}/casper/vmlinuz initrd=initrd ip=dhcp boot=casper netboot=url url=${boot_server}/casper/filesystem.squashfs console=ttyS0,115200
initrd ${boot_server}/casper/initrd

boot

but this fails when a squashfs is passed in the url. If an iso file is passed for url parameter it starts to boot by downloading the iso. But i want to boot with squashfs. Below is the error with squashfs

Begin: Trying netboot from xxx.x.x.1: ... Begin: Trying to download and mount ... wget: bad address ''
done.
Unable to find a live file system on the network

If squashfs is passed it fails with an error message "Unable to find a live file system on the network". For some reason it expects the url to be an iso. What parameter am i missing to download and boot a squashfs?

To Reproduce
Steps to reproduce the behavior:
pxe boot using filesystem.squashfs

Expected behavior

Loads the filesystem.squashfs and boots ubuntu

Screenshots

Additional context

More casper logs with debug enabled

+ '[' url '=' url ]
+ do_urlmount
+ rc=1
+ modprobe -q isofs
+ '[' n '!=' y ]
+ log_begin_msg 'Trying to download and mount '
+ _log_msg 'Begin: %s ... ' 'Trying to download and mount '
+ '[' n '=' y ]
+ printf 'Begin: %s ... ' 'Trying to download and mount '
Begin: Trying to download and mount  ... + return 0
+ basename 
+ target=
+ wget  -O 
wget: bad address ''
+ return 1
+ '[' n '!=' y ]
+ log_end_msg
+ _log_msg 'done.\n'
+ '[' n '=' y ]
+ printf 'done.\n'
done.
+ return 0
+ return 1
+ panic 'Unable to find a live file system on the network'

For some reason it expects the url to be an iso. What parameter am i missing to download and boot a squashfs?