Okay so the TFTP point on the E3000 is in the WAN port, but I'm wondering if anyone has any info on how to build (or find a prebuilt) connector that fits into the WAN port but connects to the TFTP pins/lines instead of the RJ45 pins?
I've been thinking about getting a PCB card edge connector and breaking off the sides so it'll slip on, but not sure which one would have the right size and spacing to fit the slot and pins correctly.
I might try it without such a gadget but not sure if I'll be able to make something that will stay put in the proper position long enough for me to try to get it working properly. But if there's any recommendations for going the card edge connector route, I'd rather look into that first.
I went the lazy way, opened the case and soldered to the pins on the edge/ back of the board, instead of bothering with the pins inside that rj-45 port (I'm sure Cisco/ Linksys had their special connectors for that, but I've never seen those in the wild).
Oh I've opened the case before. Back when I was using dd-wrt. I had bricked it on Christmas and I asked for help on their forums and a guru named Eko provided me a tip on a couple of pins of a microchip to short during boot to try to reset it and it worked. But I think I may have perma-bricked it now. I tried the serial method and got nothing from it. Moving the wires generated 'static' but that was the only thing that would appear in the terminal. Nothing else at all.
I am not, I described the Ci$so cable. You should use the specifications for your device. Most routers are 3 V, and this is the first time I've heard of Serial port inside of the WAN interface.
To be 100% clear, what you described is not what I believe i saw on the Wiki page:
Are you sure you didn't somehow confuse TFTP recovery via Ethernet (i.e. a lot of routers use the WAN port for TFTP for the common sense reason that it verifies you're not connected to the Internet) - versus Serial methods?
(BTW - usually you don't need to wire the +3.3 V post.)
What is the difference between the WAN port connectors and the backside connectors? There are four to each (well, backside has a fifth but it's not used according to the picture). Both have 3.3v, tx, rx, and ground. So are you saying that they are different?
I'm using this USB adapter.
Note: I am making sure to connect the right pins on the adapter to the corresponding pins on the router. Just to calm any concerns. lol
OK, using the RS-422-TTL-to-RS-232-Serial-to-USB adapter cable I see pictured from your link:
You would connect it to the Serial Interface in the following manner:
TX <> RX
RX <> TX
Ground/Ground (GND/Earth)
Use a terminal software like PuTTY, minicom, etc. to access the Serial console access (or terminal) to the router's motherboard (i.e. the "video output" screen of the router - in loose terms)
Yes, I am. TFTP is a UDP-based protocol that works over IP, and hence uses plain Ethernet in your case. This may be used in conjunction with a TFTP Server (TFTP-GET) or TFTP Client (TFTP-Push) installed on a laptop/desktop to host the firmware file (as specified in the WIki). Using plain ol' RJ-45 CAT-specification Ethernet connections - you setup up IP addresses, etc. and establish a network connection on the WAN port. This is used to load the firmware file.
3.3V is needed fir this device, the same serial port is exposed on the PCB (back/ side, as pictured), as well as inside the WAN rj45 port, opposite to the ethernet pins, where the latch is located.
Wait, I think there may be some confusion (or maybe not).
I'm not talking about the standard RJ45 connectors in the WAN port, I'm talking about the 4 gold lines on the board that are placed within the RJ45 WAN port. Same as the backside gold connectors, except there are 4 instead of 5.
Now, assuming that they are different, how would I connect the ones in the WAN port? With a spliced up RJ45 cable?
So I guess this router has the TX/RX flipped? Because I've used it before, matching them up and had it work just fine. Or would that mean that when that works, that router has them backwards instead?
From the OpenWRT Wiki under the PCB image you referenced: There is also a serial connection on the PCB inside of the WAN port. Serial port settings are 115000@8N1.
Yep, those pins are not Ci$co-compatible, they are not RJ-45. They are completely outside of the RJ-45 hole. At one time, they made RS-232 Serial interfaces with RJ-45 ports. I think the notion that RJ-45 can be used to make the serial connection caused the confusion.
Correct, it's the same port, just four parallel (tiny) traces visible through the wan port (where the notch for the rj45 plug's latch is located in the rj45 port). Linksys had this construct in several routers of that time - and they probably had a matching proprietary plug/ cable for it (not the rs-232c based Cisco console cable).
The traces are so small and hard to reach that I wouldn't bother, open the case and solder to the big pads on the back of the PCB.
I agree, I don't see how one could successfully soldier that without damaging/melting the RJ-45 Ethernet port above it. There was likely a factory-made jig/clip for large-scale ISP's etc to use it for loading, configs, etc. - but not available to retail/consumer users.
To be 100% clear, what you described 
Are you sure you didn't somehow confuse 
(BTW - usually you don't need to wire the +3.3 V post.)