After much trial and error, I have completed two builds of LFS 9.1. One of them can ping to another machine on the LAN, but no other networking actions are functioning. The other has a message during bootup "eth0 does not exist". I have tried numerous things to get ftp (on the working eth0 setup) to do anything other than start and stop; it cannot see other machines on the LAN even though a ping proves that the OS can reach them. Yes, I know that ftp is not secure, but this is only on my LAN and so I mostly concerned about getting what is apparently the only built-in LFS 9.1 networking function to be able to reach out to other machines. All the ftp can do so far is start/stop, display a prompt, and list the internal functions when replying to a typed-in '?' character.

Comment is invited.

Have you checked if the kernel can see the hardware?
I get:
It's also worth looking in /sys/class/network for your device.

My guess concerning your second system is that you left the network card driver out when you were configuring your kernel.

Hello, Hazel:
Actually, upon further examination, using "ifconfig -a", the interface named "enp1s8" showed up. By enabling that one, the connections started working. I agree that I missed something during the setup for the kernel build. I am starting another go at ... Thanks for your reply! :-)

Those names are given by udev, so I don't think reconfiguring the kernel makes any difference. However there is a kernel command line option that gives you back the old names for interfaces. I can't remember offhand what it is, but it is in the Book.