I installed this version of OpenWRT with little to no issues. http://downloads.openwrt.org/snapshots/ … actory.img
However, as much as i love OpenWRT, apparently I'm just leasing the router from my Cable Company (woops ). I need to get my original firmware back! https://www.charter.com/uploads/router- … 0.59CH.img
I tried the Web Interface firmware upgrader, and it spit out an error. After doing some research, I attempted an TFTP upgrade. I kept getting an error when trying the default firmware, but could flash OpenWRT with no issues. I tried to edit the Hex but I believe that it goes over my head. Any help is appreciated!
Here's the Hex if you want it!
OPENWRT
00000000h: 64 65 76 69 63 65 3A 57 4E 44 52 33 38 30 30 43 ; device:WNDR3800C
00000010h: 48 0A 76 65 72 73 69 6F 6E 3A 56 4F 70 65 6E 57 ; H.version:VOpenW
00000020h: 72 74 2E 72 34 36 38 31 35 0A 72 65 67 69 6F 6E ; rt.r46815.region
00000030h: 3A 0A 68 64 5F 69 64 3A 32 39 37 36 33 36 35 34 ; :.hd_id:29763654
00000040h: 2B 31 36 2B 31 32 38 0A 00 00 00 00 00 00 00 00 ; +16+128.........
00000050h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
00000060h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
00000070h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
Default Firmware
00000000h: 64 65 76 69 63 65 3A 57 4E 44 52 33 38 30 30 0A ; device:WNDR3800.
00000010h: 76 65 72 73 69 6F 6E 3A 56 32 2E 31 2E 30 2E 35 ; version:V2.1.0.5
00000020h: 39 43 48 0A 72 65 67 69 6F 6E 3A 0A 68 64 5F 69 ; 9CH.region:.hd_i
00000030h: 64 3A 32 39 37 36 33 36 35 34 2B 31 36 2B 31 32 ; d:29763654+16+12
00000040h: 38 0A 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; 8...............
00000050h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
00000060h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
00000070h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
(I'm looking for a direct .img that will work, or even the corrected Hex! I would help alot!)

(Last edited by zKeen on 11 Sep 2015, 00:39)

Start by reading this thread about TFTP flash and your router...

https://forum.openwrt.org/viewtopic.php?id=58848

Who is your cable company, and do you have a locked/branded router like the SureWest of the OP of that thread?  I ended up modifying a stock firmware for him, and somehow we got gim back in business.

Ah , just noticed it's a 3800 and not a 4300.  There shouldn't be any practical difference in the flashing procedure between these two models.  Can we assume you've read the wiki (http://wiki.openwrt.org/toh/netgear/wnd … lsafe_mode) about failsafe mode and recovery?  Basically, the SureWest routers are locked to only accept firmware marked for them, so they won't take the stock Netgear FW.  Try to figure out if you have a stock Netgear 3800 or if you've got one locked to your ISP firmware.

(Last edited by fecaleagle on 11 Sep 2015, 00:26)

[SOLVED]
Thanks for your quick reply, i had the locked Charter ISP version.
I tried everything with TFTP, but it didn't work. I had to strip the first 32 bytes with UltraEdit and then change to a .trx file. Then, i used the OpenWRT flash utility in LUCI to upgrade!
Now everything is fine. I will probuably use my second router in order to expand my network with OpenWRT, because it truly is a excellent firmware. Thank You!

[SOLVED]
I was having the same issue as the OP today and happened onto this post.

Was able to get the stock firmware loaded  https://www.charter.com/uploads/router- … 0.59CH.img

But in my case what worked was to remove the first 128 bytes from the above file and then rename it to a ".bin" file.  The resulting file was accepted by the OpenWRTs firmware upgrade webpage and flashed as expected.  I used Notepad++ and the hexeditor pluging to do this but other editors will work as well.

This procedure I think is needed only for Charter locked WNDR3800.  The model number on the bottom says WNDR3800 but the charter firmware says WNDR3800CH on their web interface.  Thanks a lot Charter for making things complicated for no reason.

Great to have this thread and other to consult with :-)