I am having issues restoring original firmware. I have a netgear R7500v1. I was able to upgrade to openwrt.
OpenWrt
Model
Netgear Nighthawk X4 R7500
Architecture
ARMv7 Processor rev 0 (v7l)
Firmware Version
OpenWrt 18.06.2 r7676-cddd7b4c77 / LuCI openwrt-18.06 branch (git-19.020.41695-6f6641d)
Kernel Version
4.14.95
I have tried restore the netgear firmware via openwrt restore, Backup and "Flash new firmware image". All give me an error {The uploaded image file does not contain a supported format. Make sure that you choose the generic image format for your platform.| about the file I am using which is a .img. I have also tried the 30/30/30 with the router and the openwrt firmware is still there. Last thing i tried was to TFTP the router with netgear .img file. TFTP has an error that router is not replying. I can ping the router while in TFTP mode.
Using tftp is required, given that the flash partitioning differs between the Netgear OEM firmware (2 MB kernel + 22 MB rootfs) and OpenWRT >=18.06.0 (4 MB Kernel + 20 MB rootfs). The exact procedure should be similar to the one used for the r7800 - and forget about urban myths like 30/30/30.
Thanks for the reply! When i try to TFTP i get something like "no response from,,," . I can log into router and see openwrt. I can ping router. I have my LAN settings set up for default ip 192.168.1.X subnet. my pc is 192.168.1.10 and router is 192.168.1.1 . pc gateway is set for 192.168.1.1 . The only thing i don't know for sure but have tested is that when TFPT to router is it the netgear firmware or openwrt firmware TFTP is authenticating to? if netgear I should use "password" as pw and if openwrt then pw is "blank" . I have tried this with the results mentioned above. I like openwrt but I loss the use of my 5ghz radios. I wanted to try DD-WRT.
Neither, tftp push-button recovery is provided by the device's bootloader (u-boot in this case, never touched by OpenWrt - so kept straight verbatim from the factory).
using 192.168.1.1 for router, pw is "password" TFTP gets about 2/3 the way and keeps popping error "unable to get response from the server" . router is responding to TFPT, i can see router lights blinking to upload. As a test I use a completely different target ip and the router light reaction was different. However the error message was the same???
This does not make sense, there is no password authentification involved with tftp.
However, to ease the process you can put an unmanaged switch between router and your client running the tftp client - this avoid link down/ link up events and link (re-)training during the reboot.