[pugazh]

I tried multiple methods to revert back to Netgear Stock Firmware with no success. After rebooting/power cycle, router retains DD-WRT image.

All below steps I tried with LAN cable connected to router's LAN1 port with Static IP Address 192.168.1.10 set in Windows.

1. Using Administration -> Firmware Upgrade method.
Using latest firmware version R6850-V1.1.0.88_1.0.1.img fails.
Using oldest available FW version R6850-V1.1.0.52.img succeeds in uploading the image within DDWRT upgrade GUI. But after reboot only DDWRT image persists

I tried both options within DDWRT GUI: After Flashing -> "Do not Reset", "Reset to Defaults" with no success.

2. Using TFTP method from windows also fails.

3. Using nmrpflash utility also fails.

I searched through dd-wrt forums but couldn't find a specific image like "ddwrt-to-stock".

Kindly help.

[the-joker]

Would you explain why you would rather go back to stock, a by default filled to the brim with unpatched security vulnerabilities firmware (without exceptions).

What problem are you trying to solve by reverting? Likely there is already a fix/solution.

What version of dd-wrt do you currently have?

and WHY, why why why or why... did I ask why already?

My kind help is, don't do it for the love of Jebus.

But it is your network, your device(s), your choice.

Welcome to the forums btw.

[pugazh]

Hi the-joker, thank you for welcoming. Glad to see your reply.

Let me explain the issue.

I have two ISP WAN with their respective modems. I am trying to use R6850 as a dual-WAN router with auto switch-over on connection failure (primary requirement) with load-balancing (good to have).

Though I referred multiple links for dual-WAN configuration in DD-WRT, couldn't get it working properly. There still a long way for me to understand dd-wrt internals, iptables, scripts, firewalls, DNS server settings, cron jobs, manual configurations and testing if all these work.

I created a second WAN port. But beyond that i couldn't proceed. I couldn't ping internet through any of the WAN ports.

The script I tried from:
https://wiki.dd-wrt.com/wiki/index.php/Dual,_Triple_(and_probably_quad)_WAN_with_multiple_active_WAN_links_and_source_routing

DD-WRT image for R6850 I used:
Downloads › betas › 2022 › 06-10-2022-r49139 › netgear-r6850 › r6850-webflash.bin

I looked at OpenWRT for R6850 and it seems to have a package for dual-WAN. So just wanted to try it out in this case.
https://openwrt.org/docs/guide-user/network/wan/multiwan/mwan3

I just want to switch to stock so that I can install openWRT because imaging openWRT in DDWRT also fails.
https://openwrt.org/toh/hwdata/netgear/netgear_r6850

[the-joker]

It should be possible, there is a nvram setting for enabling dual WAN, nvram show | grep wan_dualaccess which is set to 0

It seems to be used specifically https://github.com/search?q=wan_dualaccess&type=code for VPN/L2TP so it may not be what you need and be specific to a router target.

However I dont have any experience with DD-WRT and dual WAN setups. but presumably you need to assign a switch port to the secondary WAN.

But sure, try OpenWRT indeed you will need to revert to stock, so wait for someone else to chime in they may know a a web revert file.

OpenWRT is safer that stock anyday. Still I prefer DD-WRT, since my needs aren't so extraordinary.

[apvm]

[the-joker]

Following the instructions above, also, put a switch between router and pc and disable any firewall and optionally disable real time protection for your antivirus.

[pugazh]

Hello apvm, the link you shared is the one I referred previously also.
https://kb.netgear.com/000059633/How-do-I-upload-firmware-to-my-NETGEAR-router-using-a-TFTP-client-on-Microsoft-Windows

I did 3 things this time as suggested by the-joker:
1. connected my PC to router through an unmanaged switch.
2. turned off the firewall
3. turned off realtime protection in antivirus.

I used the oldest firmware from netgear R6850-V1.1.0.52.img
But even after multiple tries I couldn't get the tftp working. Moreover, the netgear KB article says power led will lit orange & white, whereas R6850 has all LEDs to be green.

then, I tried nmrpflash utility
https://github.com/jclehner/nmrpflash

I switched the LAN settings in PC from fixed IP to DHCP.

And it worked. Compared to my previous attempts, this time nmrpflash utility took more time and printed out all the lines including "Reboot your device now".

Now the router is back to stock firmware. Thanks, the-joker, apvm

I find nmrpflash utility to be better, because the uncertainty on when to press the put button in tftp utility is avoided.

I also came across this post, where an user seems to have succeeded in using dd-wrt web-GUI firmware upgrade option using older netgear firmware.
https://community.netgear.com/t5/General-WiFi-Routers-Non/nmrpflash-How-To/m-p/1736401/highlight/true#M132574

[the-joker]

Marking as solved and good luck openwrt side with your dual wan setup