@Soapie hi and welcome to the forum
-
When you want to boot from an external drive, that external drive also has to have an
$ESP
partition the UEFI-BIOS needs to be able to read.
Otherwise the UEFI-boot entries pointing to the external drive will be silently removed on reboots…- This is as far as i know intended behavior of the UEFI-BIOS’s for removable-drives.
- If the removable drive has it’s own
$ESP
which instructs the UEFI-BIOS to create those entries again, they will be re-added.
-
To make grub use the external harddisk to load it’s needed configuration it is using a
grub.cfg
file inside the same directory asgrubx64.efi
inside the$ESP
of the respective drive the UEFI-BIOS used to execute grub.
So to assist further you need to start providing some info about your setup…
- lsblk -fa
- efibootmgr --verbose
- Contents of grub.cfg inside the
$EFI
of both hard-disks if you have both.
Else only the one your computer has and mention it’s location.
(This is not the same file as/boot/grub/grub.cfg
!)
Yes bootloaders can be a pain