On Sun, Jun 24, 2012 at 6:36 PM, <joe@actionline.com> wrote:

What do I need to do to get an ethernet connection?

I have an ethernet connection on two computers plugged in to my motorola
modem/router (there are four ports) but another computer plugged in to one
of the open ports does not get a connection. I can get a wireless
connection on the same computer, but no wired connection.

Under network settings, I see the following:
(*) Automatic IP is checked
( ) Manual configuration is not checked

IP address is grayed out
Netmask is grayed out
Gateway is grayed out
[ ] Get DNS servers from DHCP was checked
but I unchecked it and tried 206.67.222.222 and 220 for DNS servers 1 and 2
(that didn't help)
(*) Allow users to manage the connection is checked
(*) Start the connection at boot is checked
(*) Enable traffic accounting is checked
Under "Advanced" settings: IP settings
Search domains [ (is blank) ]
DHCP client [ dhclient ]
DHCP timeout (in seconds) [ (is blank) ]
[*] Get YP servers from DHCP is checked
[ ] Get NTPD servers from DHCP is blank
DHCP host name [ (is blank) ]
Metric [ 10 ]
MTU [ (is blank) ]
[*] Network Hotplugging is checked
[*] Enable IPv6 to IPv4 tunnel (was blank; I tried checking it)

Why does Linux make all this so convoluted/complex/complicated
instead of pre-setting everything so it all "just works"?

Let's get some background to answer your question as to why Linux makes all this so complicated:
What distro are you setting up?