Asus RT-N66U flashed with RT-AC66U firmware

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nos

Occasional Visitor
This n66u was mistakenly flashed with latest ac66u firmware. It took the flash well and, while I didn't set it up, it appeared operational. I then tried to flash 374.43_49E4j9527 via web interface and ended up in boot loop. Since then I've tried 374.43_47EBj9527, big and mega DD-WRT releases, latest ASUS N66U release, along with two Tomato forks. It was the Tomato forks that actually got me a CFE(??) web interface @ 192.168.1.1. And that's where I've been stuck since. I can reboot and clear NVRAM from this interface, but firmware uploads changes nothing. I've only gotten ASUS' recovery utility to work twice, and it seems to flash completely, advising to wait for unit to reboot. I tried tftp with the various downloaded firmwares; it takes the flash after multiple attempts due to constant reboots, but nothing changes. Still have that CFE interface, but useless at this point. Only lights on router is steady power and connected LAN port. When flashing, LAN port remains lit, but Power light goes out. Looking for advice on how to proceed. TIA.
 

ColinTaylor

Part of the Furniture
When flashing the firmware via the CFE the N66U takes a long time for it to write the data, about 45 minutes typically. During this time the browser will time out and probably say it's failed. Ignore that and just be patient.
 

nos

Occasional Visitor
When flashing the firmware via the CFE the N66U takes a long time for it to write the data, about 45 minutes typically. During this time the browser will time out and probably say it's failed. Ignore that and just be patient.
Of the few times I thought I had successful flash via CFE, page displayed wait for reboot. I guess 1/2hr wasn't long enough. Also, just noted on last attempt that recovery utility app rejects official ASUS firmware ("unnamed file not found", or words to that effect)
 

Adooni

Senior Member
yea, go to mini CFE and then clear nvram. After nvram cleared from mini CFE upload correct soft - it can take easy 1h sometimes even 2h. You need to be patient and wait for router reboot.
 

nos

Occasional Visitor
yea, go to mini CFE and then clear nvram. After nvram cleared from mini CFE upload correct soft - it can take easy 1h sometimes even 2h. You need to be patient and wait for router reboot.

Did that once again yesterday, uploading official ASUS firmware and came back hours later to see message on interface asking to wait for reboot. Left it overnight, pressed continue this morning only to have CFE page load again. What would or should be "correct soft" since every one I've tried so far is not working?
 

ColinTaylor

Part of the Furniture
Did that once again yesterday, uploading official ASUS firmware and came back hours later to see message on interface asking to wait for reboot. Left it overnight, pressed continue this morning only to have CFE page load again. What would or should be "correct soft" since every one I've tried so far is not working?
Rather than pressing continue just power off the router, wait 30 seconds and turn it back on. What happens now? Does it boot into an OS or go to the "ASUSTek - CFE miniWebServer"?
 

Adooni

Senior Member
it is possible that the latest wrong soft you put in changed CFE.

I would try very old RMerlin soft for example RMerlin
or even tomato tomato - this is much smaller file - possible it will note be successful but after it try again RMerlin.

After mini CFE upload and wafting you can try 30/30/30 - I know people will say it is not working for this router but I had situation with AC56U it helped.
 

nos

Occasional Visitor
Rather than pressing continue just power off the router, wait 30 seconds and turn it back on. What happens now? Does it boot into an OS or go to the "ASUSTek - CFE miniWebServer"?
I have been shutting it down via power switch and pulling AC. Eventually I regain CFE web interface to do it all over again. No joy yet.
 

nos

Occasional Visitor
it is possible that the latest wrong soft you put in changed CFE.

I would try very old RMerlin soft for example RMerlin
or even tomato tomato - this is much smaller file - possible it will note be successful but after it try again RMerlin.

After mini CFE upload and wafting you can try 30/30/30 - I know people will say it is not working for this router but I had situation with AC56U it helped.
The CFE is still AC66U, and won't even take that firmware
 

ColinTaylor

Part of the Furniture
The CFE is still AC66U, and won't even take that firmware
Flashing the wrong firmware doesn't change the CFE. The CFE is entirely separate code in its own partition.
 

Adooni

Senior Member
I do not want to argue but ASUSWRT soft have not only firmware but CFE too and it is possible that loading new software CFE will be updated.

Try to put very old RMerlin I provided link in post above.

Can you connect to router any way putty, TFTP etc? that you could replace CFE? Try to find in web or ask some one on this forum to provide CFE for your router. As you can log to miniCFE it should be possible to rescue your router.

here for example is shown how to use TFTP to load new CFE to router https://openwrt.org/docs/techref/bootloader/cfe - I was able to recover from wrong soft upload WRT54G using command "flash -noheader : flash0.trx"
 
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nos

Occasional Visitor
I do not want to argue but ASUSWRT soft have not only firmware but CFE too and it is possible that loading new software CFE will be updated.

Try to put very old RMerlin I provided link in post above.

Can you connect to router any way putty, TFTP etc? that you could replace CFE? Try to find in web or ask some one on this forum to provide CFE for your router. As you can log to miniCFE it should be possible to rescue your router.

here for example is shown how to use TFTP to load new CFE to router https://openwrt.org/docs/techref/bootloader/cfe - I was able to recover from wrong soft upload WRT54G using command "flash -noheader : flash0.trx"

I've been able to TFTP various firmware onto device, but nothing changes; still eternal boot loop. Unable to connect via telnet or any other protocal other than http to CFE interface. "flash -noheader : flash0.trx" requires access to serial console and I have no cable, nor even looked up connection points.
 

Tech9

Very Senior Member
it is possible that loading new software CFE will be updated.

I believe one of my AC86U units got CFE updated after firmware update, but I don't remember what firmware version did it.

I've been able to TFTP various firmware onto device, but nothing changes; still eternal boot loop.

Do you clear NVRAM after every firmware flash?
 

Adooni

Senior Member
I had just ones satiation that after soft update via miniCFE I left router for 2 days (weekend) with boot loop and after so long time it boot to AsusWRT - to be honest not sure why

and ones when I put wrong CFE to AC56U I was able to start mini CFE only and I just clear nvram and put correct RMerlin soft 378.55_0 for about 6h - just miniCFE nvram clear, soft load 5min waiting then 30/30/30 (that should not work for this router) and until I was not able to log to router only miniCFE again.

I am just telling you never know what will work and when,
 
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nos

Occasional Visitor
I believe one of my AC86U units got CFE updated after firmware update, but I don't remember what firmware version did it.



Do you clear NVRAM after every firmware flash?
Yup, via WPS & power button combo prior to, and after flash
 

Adooni

Senior Member
no, you should clear nvram via miniCFE - you have there option : Restore default NVRAM values. As your CFE changed it is possible that WPS + power in not clearing nvram.
 

nos

Occasional Visitor
no, you should clear nvram via miniCFE - you have there option : Restore default NVRAM values. As your CFE changed it is possible that WPS + power in not clearing nvram.
Been doing that also when trying to flash via that interface.
 

Adooni

Senior Member
I think the only idea different than JTag is to use AFR Asus Firmware Restoration http://tomato.groov.pl/tools/UT_RT_N66U_B1_4239.zip at least 2-3 times for each RMerlin soft available https://sourceforge.net/projects/asuswrt-merlin/files/RT-N66U/Release/ then the same for all softs at ASUS web and just have a hope one of this soft will modify CFE.

just one advice when you use AFR or miniCFE etc always use Firefox for 1st login and I always use miniCFE via Firefox too. I do not know why but very often I got issue to 1st time log to router via Chromium based web soft (Chrome and similar like Edge etc.). Sometimes is not showing even logging page just hang, show connection not available etc.
 
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nos

Occasional Visitor
I think the only idea different than JTag is to use AFR Asus Firmware Restoration http://tomato.groov.pl/tools/UT_RT_N66U_B1_4239.zip at least 2-3 times for each RMerlin soft available https://sourceforge.net/projects/asuswrt-merlin/files/RT-N66U/Release/ then the same for all softs at ASUS web and just have a hope one of this soft will modify CFE.

just one advice when you use AFR or miniCFE etc always use Firefox for 1st login and I always use miniCFE via Firefox too. I do not know why but very often I got issue to 1st time log to router via Chromium based web soft (Chrome and similar like Edge etc.). Sometimes is not showing even logging page just hang, show connection not available etc.
I have tried RT-N66U_380.70_0. Haven't tried any earlier release. I've resigned to jtaggig it

 

nos

Occasional Visitor
Got it successfully flashed with older tomatousb firm. Good thing too since it seems jtagging may not have been possible.
 

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