It is always a struggle to show the grub menu, and a lot of answered questions on that.
The answer seems to be holding shift, but that doesn't work on serial console (actually serial over lan)
I have tried spamming space and escape to no avail.
This is a server which takes quite a long time to pass bios, and it makes it even more difficult and time consuming.
Is there a good solution to enter grub reliably?
Obviously editing /etc/default/grub would help, but now it is too late.