UEFI boot and sanhook

[NiKiZe]

You have still not really explained what it is that you want to do - and the actual issue when you do that.
From my perspective this should all just work.

I don't fully know what multiboot is, but if that is an efi application that has something that tries to do anything with the network interfaces you should probably expect that to cause issues. (If that is the case then you might want to report that as a bug to them)

Again I would strongly suggest that you check tcpdump, and maybe monitor link state, that should tell you if there is any kind of network issues (and most importantly issues caused by anything on the client itself)

Also I would not be surprised if efi shell refuses to deal with a disk, and is only able to handle partitions with efi compatible filesystems. (but again this depends on the firmware support, rather than efi shell itself)