Grub4dos via pxe - black screen. What could be the problem?

Question

GRUB

Good day to all!
Available:
Freenas (like tftp and iscsi), mikrotik rb-20011uias (like dhcp) and a computer that should boot via iscsi
Downloaded grub4dos0.4.4, put grldr and menu.lst in the tftp
folder passes dhcp redirection, accesses tftp and that's it. blinking cursor, no messages on the screen.
There was a suspicion that the loader could not access tftp itself and read menu.lst, but I don't know how to check such an idea.
Then I switched to a more recent version - g4d0.4.6, now an error began to appear - missing helper.
Google didn't help me find a solution.