I installed Ubuntu 18.04 in UEFI mode on my external HDD to run on my Dell XPS 15 9570 which has Windows 10 natively installed. I didn't want to dual boot from my internal SSD since I didn't want to change to AHCI and make any drastic changes to the device in general. The HDD is 1TB but I gave Ubuntu about 256GB and formatted the rest to NTFS so I could also use it as external storage for random files on both operating systems.
The install went perfectly. UEFI gave me no real issues. I left Secure Boot on and didn't add the option to boot from Legacy ROMs. I just needed to add Ubuntu to the boot sequence in the UEFI settings/BIOS and set it to load Ubuntu first so when the HDD is connected it loads to Ubuntu and when it isn't it loads to Windows 10 for a plug-and-play effect.
This works very well. However, there is one issue. When I read the HDD in Windows which loads the Ubuntu EFI partition and the NTFS partition separately, it seems to delete Ubuntu from the boot sequence. To add it back I need to re-add Ubuntu from the UEFI settings. I'm not sure what is causing this. I suspect it has something to do with Windows seeing the Ubuntu EFI partition.
Now this isn't a major issue. I could re-add Ubuntu to the boot sequence every time I decide to access the NTFS partition on Windows. But I would prefer not to fiddle around with the BIOS too much.
Has anyone experienced this? Any solutions?
