[PLUG] Network puzzle

[John Jason Jordan]

I have a network problem that has me baffled. 

I will start by describing my home network, from the cable modem on
downwards. 

1) Cable modem
2) Router
3) Two switches and a WRT54G
4) Patch panel mounted on the wall
5) Ethernet jacks throughout the house
6) Two computers, an HDHomeRun TV tuner, and four laser printers

First, everything is gigabit rated, including the house wiring and
jacks (CAT6), except the four laser printers. I did the house wiring
myself when the walls were all open, and this is the only network
wiring I have ever done, leading to the conclusion that wiring faults
are more likely than usual.

There is a patch cord from the cable modem to the WAN port on the
router. The router has four other ports, three of which are connected
to Switch 1 (purchased new), Switch 2 (a $10 Free Geek special), and the
WRT54G. Both switches are 8-port gigabit switches. The router has
reservations for the MAC address of the two computers (the laptop has
three MAC addresses, go figure), the HDHomeRun, the WRT54G and the
cable modem. All are 192.168.0,x and the router is set to use x=0 to
100 for the printers, where the reserved addresses for the various MAC
addresses are all above x=100. Each printer has its IP address set
manually in the printer's control panel.

There are cables from the switches to jacks on the patch panel which,
in turn, connect to the jacks throughout the house. When I turn on a
printer the corresponding light on the switch comes on. One of the
printers is on my desk and its connection is through switch 1. The
other three are in another room and they connect through switch 2. In
fact, those three printers are the only things on switch 2. 

Just before OSCON I wanted to print to one of the printers in the other
room, a Phaser 7400. Its IP address is 192.168.0.40. I turned it on and
sent it a print job. Nothing happened. I looked at the printer's control
panel expecting to see "Processing job" but it just said "Ready." I
noted that the light for the printer on switch 2 was not lit up. I
could not ping the printer. Yet this connection worked perfectly as
recently as a couple weeks earlier, and no changes to the network had
been made.

Wondering if switch 2 had gone to network heaven I went back to the
other room and turned on both the other laser printers (both older HP
models). The lights on switch 2 for both those printers lit up. Both
printers responded to pings. Thinking that perhaps one of the ports on
switch 2 had failed I tried the other ports. No matter which port I
plugged the Phaser 7400 into the light never came on, and no matter
which port I plugged the other two printers into their lights always
came on. 

Now, at this point one must conclude that something went awry with the
wire to the Phaser 7400, probably at the patch panel or the jack in the
other room. I wiggled both and swapped the patch cords, but no joy. And
then I decided to plug the Phaser 7400 cable into switch 1. Its light
came on. I was able to ping it and print to it.

So here's the big question: Why would the Phaser 7400 suddenly be
unable to connect through switch 2? 

Additional data: I have another router, not gigabit rated, but set up
the same as the one I usually use. I swapped them, but it made no
difference. I also have another 8-port switch, also not gigabit rated.
I swapped it for switch 2, but it also made no difference. If it
matters, switch 1 is a DynexDX-GB8PRT and switch 2 is a D-Link
DGS-1005D. The non-gigabit switch is a D-Link DSH-8.

Any suggestions welcome.