Here we go:
My WNDR4700 was working like 10 years with 1.0.0.56 native firmware.
Yet it cause bandwidth drop from 200mbps to 12mbps in 25 days, and that is annoying to make manual restarts.
So i decided to check OpenWrt FW, downloaded an [23.05.RC2](https://
A brief moment of Joy - wait 3 minutes until it is applyed - last words from router in admin panel.
It started blinking green power LED and do nothing.
Here in the forum i discovered partial information about recovery and tryed it:
Enabled TFTP in Windows10.
Connected LAN to WAN/LAN4 ports - network unidentified.
Made manual settings for Ethernet3 ipv.4 (192.168.0.1/192.168.1.1)
And made an string for file push.
tftp -i 192.168.1.2 put H:\openwrt22035.img 192.168.1.1
Connect request failed
(where i shortened another file, thought recommended as recovery, and put it into root of an drive H:)
The kernel on recent OpenWrt builds is too big for the standard settings and a change in the uboot environment is needed to be able to make it work. See the link above for the details.
Following @konus ' advice, it is unwise to try to flash directly the latest stable, and furthermore a snapshot on such an old device. You may face partition layout change, kernel size and many other issues that have occured in the meantime since first support.
Simple advice would be to flash an early version of OpenWrt, than upgrade one step at a time. At each step you may face a new problem that requires a change.
Finally when you would have solved all issues and gain experience on how to solve them, you may flash the latest stable. It's not even sure that it runs.
I finally got back to the WNDR4700 at my parents place and updated the bootcmd over serial. 22.03.5 works fine with the new bootcmd however upgrading to 23.05.rc2 does result in a brick. So it looks like the new bootcmd is not enough to get 23.05.rc2 to work unfortunately.
Recovery with nmrp flash to netgear stock firmware and then upgrade to 22.03.5 factory image works fine. Updated bootcmd still works and survives recovery using nmrp flash.