How to Set Up a Serial Console for NETGEAR R8000


Using serial console setup users can get access to the serial console of their router. Serial console setup finds its most important use in debricking a router. Moreover, developers may use it to extract useful debug information from their routers.

This short tutorial explains how to setup serial console for Netgear R8000.

Identify location of Serial pins on your router:

First open the case of your router. You should be able to find pins for serial communications at the location indicated in Figure1(a).

Figure1(a): Serial pin location on your router


Some R8000 router may not come with pins for serial communications. In such cases, you will have to attach the pins on your own. Go to the location as indicated in Figure1(a), where you will find a connection with the name J252 as shown in Figure 1(b). Solder the pins here carefully.

Figure1(b): Serial pin location on your router

Identify important pins on router for serial communication:

Important pins on the router for serial communication are identified in Figure 2.

Figure 2: Important pins on the router for serial communication

Identify important pins in USB-TTL cable:

Important pins in the USB-TTL cable are indicated in Figure 3.

Figure 3: Important pins in USB-TTL cable

How to connect USB-TTL cable to the pins on the router for serial communication:

The connection between USB-TTL cable and pins on the router for serial communication is explained in Figure 4.

Figure 4: Connection between USB-TTL cable and pins for serial communication

Physical setup of your serial console ends here.

Verification of the setup:

To verify your setup, start serial client on your PC with proper parameters and then power on your router. As soon as you do this, you will be able to see debug information from the router on your screen. If you do not see anything, check that all the connections have been made properly and if in doubt, reattach the cables. Verify that the Serial Client has the proper parameters for the connection.


nf.martin's picture


Does the USB-TTL cable (FTDI) need to be   a:) 1.8v     b:) 3.3v      or c:) 5.0v.

Just thought I'd ask before I,    a:) ordered the cable     or b:) burned up the router.

wick33d's picture
I would say the voltage isnt

I would say the voltage isnt the crucial part, aslong as you know wich pin sends the V and don't connect it, the important ones are Ground, RX and TX. Wich may vary depending on what cable you are using. 

I followed this with an --- ALTHOUGH! I would not recommend this one, but it did work for me. Using windows 10 (PROBLEM with driver tho, had to get a homemade driver) I did get some bluescreens stunning huh? But in the end the router is up and running.

Adafruit 4 Pin Cable (PL2303)

This is a Prolific chipset based cable. Some people have reported issues with the cable causing some issues with data corruption. You experience may vary. You will need to install the Prolific drivers. Those can be downloaded from Adafruit.

RPI Serial.png


   Board       Wire    Function
  Pin 1.....Black.....Ground
  Pin 4.....Green.....Receive
  Pin 5.....White....Transmit


Just remember when connected and you have inputs on the serial prompt (putty or minicom or w/e)

1. Restart the router

2. Press ctrl + c untill you see CFE

3. Type tftpd - To start the TFTP server

4. Connect the PC to a lan interface and give it a static ip, preferebly but you can put anything withing -

5. Use any kind of TFTP client and put the "R8000-V1.0.3.4_1.1.2.chk" (Firmware file) to the server

Using windows build in TFTP (YOU CAN ENABLE THIS IN PROGRAMS AND FEATURES) from command prompt

tfpt -i put R8000-V1.0.3.4_1.1.2.chk 

Make sure you are in the same folder from i did put mine in the root of C: so all I did was cd C:\ and then did the TFTP put command.

after a while you get a succes message, if not try again. The router might have timedout.

6. Using linux from terminal


> binary

> put R8000-V1.0.3.4_1.1.2.chk

Note that you will need to be in the correct directory when you begin.

7. Enjoy the ride.

Ivirgen79's picture
Is possible to do the unbrick

Is possible to do the unbrick process on a MAC via terminal?

Chrdur21's picture
Hi i enjoy my new wifi route

Hi i enjoy my new wifi route it great

Static_Rocket's picture
Well this is going to sound
Well this is going to sound odd, but I am having some boot issues with my Netgear R8000 while I have an adaptor connected to its JTAG port, and by issues I mean all of it. When the ground pin on the Adaptor is connected, the power light displays white and It simply will not get past the light test part of the boot process. 
It is currently bricked (I assume so at this point, all pings return "Host Unreachable) after updating from one of the recent Kong builds to a direct dd-wrt version and adjusting the clock speed. It somehow glitched out and set the clock speed to 0, but during the boot process it ignores it and sets it back to 400mhz. I found this out by powering on the router with the ground of the JTAG adaptor disconnected and then plugging it in immediately after the light test phase of the boot. This gives a short burst of information before freezing, but this burst is inconsistent and sometimes contains something new, but never the whole thing. I spent a whole week messing with this thing and I just can't figure out what is going on. Any help would be appreciated.
(There should be a photo here)
emailt31's picture
Just tried latest 3rd Jan

Just tried latest 3rd Jan 2017 kong release


Its obviously not bug free!!!


After configuring a wifi password it caused a continous reboot loop :(


So I shall be reflashing it after wiring in a UART serial cable as per above to recover the device. Think I will go back to stock firmware as this isn't very stable !



emailt31's picture
Ok did this and managed to

Ok did this and managed to successfully recover my R8000 router, while adding a very useful serial diagnostic log capability.

There are a few details missing here.

Dismantling the case to fit the USB to Serial UART adaptor.
1. When dismantling the case there is one further screw hidden behind the product sticky label on the underside of the device. Also be careful
disconnecting the ribbon cable for the strip of LED lights and Wifi, WPS buttons since it could easily be damaged with force. As conventional on ribbon cables there is a little plastic tab which flips up allowing the cable to easily be removed.

Serial Connection to PC
1. Very little information was present on the serial settings for the connection. I found the ones which CFE for the R8000 are configure with are;
 Baud rate: 115200 8 bits, No parity, 1 stop bit. (or 8-N-1)
 And just a FYI, my USB to Serial UART converter was a 3.3v.

2. I used PuTTY on Windows, or minicom on Linux. Under Windows you can find the serial port to use to connect from Device Manager (Ports), COMx.

Commands in CFE
3. Once your connected you should see the bootloader logs.

4. Pressing multiple times CTRL+C to abort the CFE boot loader autoboot and drop you into a console window of CFE boot loader (Broadcom's open source bootloader).

5. You can then type in 'help' to see a list of commands, I used 'nvram reset', or if you want to learn about the command 'help nvram'.

6. Once you reboot (assuming flash is ok but configuration was the issue like in my scenario which was resulting in a Kernel Panic and reboot)
if you can login. Default DD-WRT login credentials are username 'root' and password is 'admin'. Once logged in you can use the command 'erase nvram'.

7. Once I did this I was able to login via RJ45 connection and get back the administration pages and prevent the kernel constantly going into a reboot loop.

I'd seriously recommend building the stack from source-code if you intend to use this release on your device since its not very stable and will require some further debugging. Good luck!

RebeccaV's picture
I also bricked my R8000

I also bricked my R8000 trying to setup tomato. I managed to connect the R8000 with a USB TLL cable. From top to bottom: Red/Black/Green/White.

I set up Putty on COM 4 (Same as in Device management Prolific: COM4) On the R8000 i connected RJ45 cable (port 1) to laptop. I started up putty but nothing happens when i push and hold ctrl C. When i shut down putty it asks me if i want to close the session.

The only thing i see is a green block in putty! I didn't connect the power cable on the R8000. The botton light stays amber. Please can and will somebody help me to solving this problem?

Many thx in advance, Rebecca

johnnyde94's picture
when i try connect via serial

when i try connect via serial and tftp i get the error: 

reading:: failed: I/O Error

demonstrative's picture
Bought a router from someone

Bought a router from someone else who said it was working well. turned out brick. 

Bought a USB TTL cable and followed the steps stated above. 
Tried a few times and the results were the same. 
[From PuTTY]
Startup canceled
CFE> tftpd
Start TFTP server
Reading ::
Router shuts down. 
Any help will be appreciated. Thank you!
dundeee1906's picture
Am i tripping, or does the

Am i tripping, or does the pictures of the serial connections and the labeled ends from the cable not match?


christianwis's picture


I have the converter "usb-ttl" and made all the connections in the serial port of the router. If I access via ethernet I can ping and respond correctly.

But if I want to transfer the file through the COM2 port I do not understand why the command has an IP address (

This is the command that says:
tftp -i put R8000-V1.0.3.4_1.1.2.chk

I clarified that I have the original firmware ... I'm not using the dd.wrt

If you can help me, I would appreciate it.


Static_Rocket's picture
You aren't sending the file

You aren't sending the file over the "USB-TTL" serial link. That is impractical. Instead you are using the TTL connection to command the router to host a TFPT link between the router and the computer over the ethernet connection (which you know is working because you can ping the router) and sending the file over via that link.

redtubey671's picture
Hate to bump an old thread,

Hate to bump an old thread, but I flashed back from Merlin to ofw, and now my R8000 won't load any firmware. It is currently stuck on the with no way up update. I've tried Merlin, netgear, dd-wrt, all loaded through tftp as shown above. After the firmware is sent, the router goes back to "Reading::" and doesnt p
Move forward until it times out and reboots to Any ideas?


sabhain's picture
To add to all of the good

To add to all of the good information here .. I just did this process to move my R8000 to DD-WRT and was getting the "not allow to downgrade firmware" error.

I followed emailt31's recommendation closely, with a few tweaks to make it actually work:

#1 - I found no need to open the case to connect to the jumpers on the board.  Simply taking the black plastic pieces carefully off the pins on my USB-TTL cable gave me the ability to drop them right on the pins through the case.  I didn't open it up at all .. and this took about 5 minutes to accomplish:

#2 - I used minicom on Ubuntu 14.04.  It worked well.  You just need to use dmesg to identify if your TTL is recognized.  Ultimately it ended up being located at /dev/ttyUSB0 for me.

#3 - In order to send the Ctrl-C to the router from minicom, you need to turn Hardware Flow Control to OFF.  Then you can send the CTRL-C easily.

#4 - It's not so clear in any of the lists, but you need to create the serial link as shown here .. AND AT THE SAME TIME, an ethernet link from a computer to the router.  You'll do the tftp put command from a different terminal (same computer possibly) than the CRE serial connection.

#5 - To get the system to flash my desired firmware, I needed to do the following to avoid the "not allow downgrade" error.

  1. Connect to the router via serial (as demonstrated above, and hit Ctrl-C to get to the CRE prompt.
  2. I used the command "flash -noheader : flash1.trx" (no quotes) to start the process on the router serial side.
  3. From a different terminal, I connected to the router with tftp, then used the "binary" command to set to binary.
  4. I sent the latest Kong build in binary.  Skipped the CHK step.
  5. Note that I needed to do #2 and #4 almost at the same time.  I found that #2 times out in about 15 or 20 seconds, so I had #3 actually done, and the command to send the bin file already typed in .. then hit enter in the CRE command followed by enter on the tftp put command.

That worked for me in this combination.  Good luck, and remember, all caveats apply.  You're on your own if you do this .. and there's no warranty to these notes I'm providing.  Credit to the posters on the following link for posting the information that made this work for me (#2 above especially was critical information):

Good luck.

repoman576's picture
i did a search on google and

i did a search on google and was brought to this thread.  i have the netgear 8500 with a bootloop.  ive been trying to follow things that are suggested in this thread but my skill levels are not quite up to you guys here.  i bought the usb ttl cable from ebay and im not having any success.  its most likely due to the fact that i may be skipping many step as it appears to me that most of you guys in this thread have a clue to whats being said and suggested.  is there a step by step for dummies on how to fix this?  would appreciate any help


thank you

ggwashburn's picture
Thank you all for the good

Thank you all for the good information posted here.  I have an R8000 that I"m trying to set up to run dd-wrt.  I have managed to get the usb-serial cable connected to the router and PC and can see the debug text flow accross the screen when I reboot the router.  I think I have set the parameters correctly, including flow control settings to off.  For some reason I cannot get the serial console to display the CFE prompt.  Every time I reboot the routher and start hitting Control-C, the debug text just keeps flowing.  I have tried Windows 10 with Putty, and Ubuntu 18.04 with minicom.  Using both methods, I can see the console debug info on the terminal window, but Control-C does not break the reboot cycle or take me to a CFE> prompt.  What am I doing wrong?  I'm assuming the cfe prompt looks something like this "CFE>" and is wating for my input, but I never see that.

ggwashburn's picture
I fiinally got the Control-C

I fiinally got the Control-C to work and the console came up to the CFE> prompt.  Reversing the green and white wires on the Adafruit USB-TTL cable was the thing that finally worked.  I assumed that since I was seeing the debug text flowing across the console terminal screen that the RXD and TXD were connected correctly, but somehow the text still made it to my terminal screen while having the two pins reversed.  According to the labeled photo of the board above, pin 1 is closest to the back of the board where the power switch and network connections are.  So the connections that worked for me are as follows:  Red wire not connected and pin 1 not touched.  Black wire connected to pin 2 (ground).  White wire connected to pin 3.  And green wire connected to pin 4.  Like one of the other commenters, I was confused about the meaining of RXD and TXD and whether to conntect to RXD of the cable to the TXD of the board or TXD to TXD.  The USB-TTL cable I used was Adafruit product number 954  Once the wires were connected to the correct pins, I was able to switch on the router and continueously hit Control-C and after a few seconds got the CFE> prompt.  Tomorrow I will try to use the flash command and load a custom firmware with TFTP.

ggwashburn's picture
Just wanted to follow up and

Just wanted to follow up and report that I was able to flash the latest Kong build using the steps from sabain's comment, steps 1-5.  I'm very happy with the firmware so far, and following sabain's steps didn't "brick" anything.

ktb973's picture
This worked perfectly to

This worked perfectly to unbrick my R8000. Thank you!