How to restore GRUB with UEFI on an external HDD?

Question

GRUB

Installed Ubuntu 16.04 on an external hdd. grub there.
After installation, everything started with a bang. (The installation was carried out on another laptop, it was launched as a native ubunta and the one on the external one (in this case, the choice of what to run was carried out from the boot menu)). Next, installed on the win7 beech.
fdisk - l
label type - gpt
/dev/sda1 - efi sys
/dev/sda2- linux filesys
/dev/sda3- linux filesys
while parts 1 and 3 do not start with the physical sector boundary (I'm afraid I would translate it incorrectly)
restored grub according to instructions help.ubuntu.ru/wiki/%D0%B2%D0%BE%D1%81%D1%81%D1%82...
In the BIOS there are items with uefi and just like legacy + there is a standard version of ubuntu: * disk name* (I have two of these, my system and on hdd).
When you select uefi, it throws it back into the BIOS without rebooting the machine.
When choosing a legacy option, it says that there is no bootloader at all.
When choosing ubuntu: * disk name * (exactly what is external) loads my system (which is on internal media).
Thanks in advance.