Netgear R7900 possibly bricked after flashing OpenWrt 21.02.3

[fangq]

My Netgear Nighthawk x6 R7900 router has been plagued by DNS issues of the OEM firmware for some time. I finally decided to try an open-source firmware, and downloaded OpenWrt from this page

Techdata: NETGEAR R7900

I used the Netgear web GUI and flashed the openwrt.chk file, but then I am no longer able to connect to the router.

The router only has a single power LED on in red. If I connect my laptop to the LAN port, the LED of the port is led in white, but my laptop (running Ubuntu 22.04) could not get IP address via DHCP. I manually set IP address, but I could not ssh to 192.168.1.1 or any other address in /24.

I tried pressing the reset button on the router, nothing changes no matter how long I press.

I read the failsafe wiki page, when turning on my router, my power LED never blinks. I don't know if it is in the failsafe state already, or bricked.

I was also trying to revert to the OEM firmware, but could not find any documentation on how to do this (given I could not see web GUI or ssh)

does anyone have similar issues? I am appreciated if you can help me fix this.

[stmtpr]

I don't know anything about that router but shouldn't your ip address be 192.168.1.0/24 range?

[fangq]

from reading this page: https://openwrt.org/docs/guide-user/network/openwrt_as_routerdevice

I was under the impression that the default gateway IP is 192.168.1.1 and the default allowed IP range is 1.x, not 0.x. Because the DHCP did not work, so I did not really know what was the correct default range.

I just tried to manually request IP from 192.168.0.x, and set router address to either 0.1 or 1.1, but neither allow me to ssh to the router.

[stmtpr]

The reason i mentioned that range was because in your original post you said "192.163.1.1".. Notice the 163 part.

[fangq]

sorry, that was a typo.

[rwl408]

Was R7900's wan port connected to the lan port of ISP' router or modem? If it was, disconnect it and power cycle R7900. Then try to access R7900 via 192.168.1.1.

[fangq]

@rwl408, no, the uplink (WAN) is not connected.

[rwl408]

I guess the router is busted like you said. I don't have experience with R7900 although I used to have a R7000 loaded with DD-Wrt (and recently converted a R6700 to R7000). It seems that you need the CFE TFTP + serial recovery method according to the OpenWrt R7900 Techdata. From my understanding, R7900 is a Costco's version of R8000 so you can ask Netgear or DD-Wrt (supports R8000) forums for how to recovery from a bricked R8000/R7900 too.

Edit - Found this link in my browser's bookmark:
How do I upload firmware to my NETGEAR router using a TFTP client on Microsoft Windows?

[fangq]

sorry for my late reply - thanks for your comment again. I tried to connect to the router via tftp. This is what I did -

• boot up the router (flashed with OpenWrt 21.02.3)
• after flashing some of the indicators, the router shows only amber light on the top LED, no other LED is on
• connect a laptop to the router with a wire to one of the 4 LAN ports
• the laptop is set in DHCP mode (running Ubuntu Linux) - type ipconfig, shows that the laptop can't get DHCP address
• ping 192.168.1.1, failed
• set laptop to static IP (192.168.1.140), still can't connect to 192.168.1.1

is there any other ways to connect or re-flash the router?

thanks

[elder_tinkerer]

@fangq

is there any other ways to connect or re-flash the router?

Yes, there is. Get yourself a TTL-Serial-to-USB-cable, open the router and connect the router via the cable with your PC.

It's said that the R7900 and R8000 are quite similar, so maybe this would help:
https://www.myopenrouter.com/article/how-set-serial-console-netgear-r8000

Also, please refer to:

Is there a way to unbrick an r8000?

I've flashed june 03/17 firmware and somewhere during the process I believe my router bricked. On windows I tried tftp but the router was unreachable. I am not able to ssh into the router and when using ping I get host is unreachable. I do have an adafruit console cable to use. I also own an r7000 which also bricked and there is an unbrick guide on another forum. Would the steps be similar for the r8000? Would there be anyone willing to do a write-up?

and

Serial Console

I do hope it helps a bit.

[mechango]

fangq, go to https://github.com/jclehner/nmrpflash
This is the "Netgear Unbrick Utility".

I have the same router and the conditions you described were exactly the same as when I bricked my R7900. Do the NUU and make it great again!

[fangq]

thank you so much @mechango, nmrpflash did the trick! I am happy that the router is finally working again.

it turns out timing is important for nmrpflash to work successfully - when turning on the router after launching the command, I first got an Timeout while waiting for TFTP_UL_REQ.

sudo nmrpflash -i enp2s0 -f R7900-V1.0.4.38_10.0.50.chk -T 20 -t 1000
Advertising NMRP server on enp2s0 ... /
Received configuration request from xx:xx:xx...
Sending configuration: 10.164.183.252/24.
Timeout while waiting for TFTP_UL_REQ.

however, immediately relaunching the command could allow the file to be uploaded. even thought I am still getting Timeout while waiting for 0000. error, the router was able to finish rebooting and function again

sudo nmrpflash -i enp2s0 -f R7900-V1.0.4.38_10.0.50.chk -T 20 -t 1000
Advertising NMRP server on enp2s0 ... -
Received TFTP_UL_REQ while waiting for CONF_REQ!
Received upload request without filename.
Uploading R7900-V1.0.4.38_10.0.50.chk ... OK
Waiting for remote to respond.
Timeout while waiting for 0000.

thanks again!

[mechango]

Good job. BTW, at which point I bricked my router was when I tried to flash an OpenWRT to get to finally flashing a Fresh Tomato firmware. It failed on the OpenWRT stage. Can anyone help in flashing the Tomato onto a r7900?