Qubes won't boot on external SSD

I’ve tried installing Qubes 4.1.0 on a external SSD for days but it doesn’t boot. I installed it on my Desktop using a bootable USB with Etcher and the Qubes ISO. It installed on the SSD but doesn’t boot. There is no boot menu just the error message

Checking Media Presence…

Media Present…

Start PXE over IPv4…

This happens with only the external SSD with Qubes plugged in with the Windows SSD and HDD unplugged.

I’ve also tried to boot it on my HP Spectre x360 laptop. I get to the boot menu on the laptop, going for “install” or “try and install” on the laptop is even worse than on the desktop, as the Qubes installer doesn’t even work. Just a black screen with an error message.

I’ve checked the Qubes hardware list and there are some MSI Desktops and HP Spectre laptops similar to mine although they’re not green in every category. Both my computers are virtualization enabled.

Should I go for the official Qubes laptops instead? They’re expensive though. I see this one Purism Librem one is good but it doesn’t come with Qubes but PureOS. What to do now?

You may just need to change some BIOS settings so you can see the Qubes device in the boot menu. Look for a setting in the BIOS to enable Legacy Boot or enable UEFI boot or both. You can also try installing Qubes OS with either legacy or UEFI to see if that makes a difference.

Just to confirm, you used Etcher to burn the ISO onto a flash drive, then booted into that to install Qubes onto the external SSD, correct?
You can also read the Installation guide | Qubes OS to make sure you’re doing everything properly.

At the top of the black screen when running the USB with the ISO it always says

dracut-pre-udev[652]: modprobe: ERROR: could not insert ‘floppy’:

I’ve formatted the ext. SSD to both NTFS and exFAT but it just doesn’t show up in the installer. The installer starts though in both RAID and AHCI mode.