If the other laptop is directly connected to the OpenWrt laptop and it is not getting an IP address, either there is a config issue (possible, but I think unlikely if we're mostly in a default state), or the ethernet port on the OpenWrt laptop is not properly initialized. You may need to install an additional package that contains the relevant drivers necessary to use that port.
Take a look at this thread... you'll need to similarly determine what ethernet chipset is in the OpenWrt laptop.