boot command hangs

[NiKiZe]

if https was not enabled you would get "protocol not supported" so that is not the issue.

You will need to figure out what is going on.
use your non https version...

then extend it with initrd https: files, but end them with an additional filename.

initrd https://<MY_URL>/initrd.img httpsinitrd
initrd https://<MY_URL>/vmlinuz httpsvmlinuz

this should add the downloaded data to separate cpio archives - which should be available from within your started linux distro - and hopefully could be used to identify what is going on.

Another thing that you could do is to recreate the iPXE user-agent and headers with curl or similar, and see if that makes a difference.
Also hosting the files on the same service, but without https, might be helpful for debuging using tcpdump or similar.