I have tried these. Each had exactly the same result.
dd-wrt-Asus_RT-AC66U.trx (this one is the version recommended from the router database for this unit)
Been there, seen that. On the rt-ac66u you can reset to defaults aka erase nvram with the WPS button: power off, press and hold WPS button for 5 sec, power on, continue holding WPS for 10 sec, release wps.
Posted: Fri Apr 01, 2016 0:48 Post subject: Asus RT-AC66U wont load dd-wrt
So I just read another post with same issue.
Here the facts;
router firmware 18.104.22.168.378_9533-g2949056
DDWRT file, 2016/03-31-2016-r29387/asus-rt-ac66u/
I can clear nvram, then upload the above file. I get a message to manually reboot after file loads. I manually reboot then router is not loading old or new OS. Stuck on Asus recover page. I then uploaded and let it sit for over an hour, checked again still on Asus recover page. Tried manual reboot, still same issue. I can use the Asus recover tool and reload the original OS. Any ideas?
Well, no love at all on my end. I tried the WPS button holding trick to no avail. Yes, I have tried using the recovery tool, and get the same results.
What jrico is describing is exactly what is happening to me.
Right now, I'm looking the nvram contents, and it appears that the boot loader is resetting nvram entries based on what is in the boot loader. One can change them, commit them, and when the box is rebooted, the settings are reverted.
From my reading, the boot loader has these in place to prevent people from setting certain variables in nvram to change things (like region, CPU clock, etc) due to some recent FCC legislation. It's possible that earlier versions of this router were not set up like this - but the one I just picked up from Amazon - IS set up like this.
I don't know what dd-wrt does when it attempts to flash in, but is it explicitly setting/changing things in nvram that it expects to be there between resets and restarts?
I'm experimenting with building (ie - hexing up my old one) my own boot loader for this thing that doesn't do those horrible things. After I get that in place (I am pretty close), I'll give dd-wrt another spin.
I'll probably mess with it another half day or so, and then purposefully brick it before sending it back for a refund.
@alpineYJ, if you need some old cfes for ac66u, there are some here:
Have to verify your h/w version though. There seems to be different versions. _________________
Netgear R7800 kongpro 19.07 20190919 || Netgear R7000 36070M kongac (Client Bridge=5GHz, AP=2.4GHz with bridged VAP)
Linksys WRT32X davidc502 OpenWrt || Linksys WRT1200ACv1 Gargoyle 1.11.x
Linksys WRT1900ACSv2 dd-wrt 39956