barebox and dhcp
When you need to boot from TFTP, barebox will try to get an ip from DHCP (if no fixed IP was set).
If the DHCP server is not ready at this time, barebox will go back to
the main menu.
Then if you start the DHCP server and try again to boot from TFTP
directly this will fail, because we don't try again the DHCP if it has
failed previously.
Quick solution:
You need to select reboot and then the TFTP option to make it work.