Ethernet Interface disappear after exit from grub command prompt

[Wasim Khan]

Hi,

I am working on a EDK2 based UEFI solution for arm64 architecture board. I am 
trying Pxeboot to boot Linux from network.

I am doing below steps:

*         From UEFI boot Menu, select Pxeboot on a particular interface (say 
eth0).

*         After getting the grub.efi from network, select a menu entry from 
grub menu.

*         If a file corresponding to selected grub menu entry is not present on 
tftp server, grub menu is displayed again.

*         Now go to grub command prompt and run 'exit' command.

*         I am coming back to UEFI boot menu, but if I go to UEFI SHELL, 
interface eth0 is not visible in ifconfig command.

Same behavior is observed on arm64 QEMU virtual machine UEFI firmware .
http://snapshots.linaro.org/components/kernel/leg-virt-tianocore-edk2-upstream/latest/QEMU-AARCH64/DEBUG_GCC5/

Is it a bug in grub OR is it by design?
Can someone help me understand the exit process, that why exit from grub 
command prompt (after tftp fail) is making the interface down ?

Thanks,
Wasim