Problem:
You have setup a DHCP server, boot EtherBoot, but it will fail to accept an IP address from the server.

Solution:
As of version 3.0.3 of the ISC DHCP server, the value of “next-server” does not have a reasonable default any more (it used to contain the IP address of the DHCP server, which would act as TFTP server then). You will have to set it to the IP address of the TFTP server (in most cases, the same machine as the DHCP server):

next-server 192.168.0.1;

in your dhcpd.conf, somewhere in the global section near the top, will do the trick.

Problem:
gPXE is failing with an error code that is not human-readable.

Solution:
Error codes are generally internal errors. Many user errors are displayed as human-readable messages. Error codes allow the developers to identify the location in gPXE where the error is coming from. You can use the web-based gPXE Error Code Lookup or ask gpxebot for help on the IRC channel. Fully investigating an error code will require the gPXE source code. Start by looking at src/include/errno.h. Developers are often available for help on the IRC channel!

Problem:
You have created a network-bootable-image (NBI) of a Linux 2.6 (or higher) kernel with mknbi-* and want to boot it using Etherboot but Etherboot stops after loading the image and either hangs or enters an infinite reboot-cycle.

Solution:
Use wraplinux to make the NBI in stead of mknbi-*. Wraplinux can be downloaded from here. Preferably, if you can, you might want to upgrade from using etherboot to using gPXE as netbootloader.