[spaceghost]

Hi,

I've had my RT-AC66U A1 version collecting dust in a drawer and I now need it to setup an access point at work in a client repeater type of setup using both 2.4ghz and 5ghz radios on it.

I've run into the problem where I can only see the 2.4G radio and not the 5G radio.

I have read all the forum posts linked in the wiki for this device around the NVRAM issues and losing the 5G radio and I simply cannot get it to work. I have tried the following:

•Factory Reset on the lastest DD-WRT release from Jan 2026 using the GUI
•Downgraded to 26339 (no 5G)
•Multiple Factory Resets on 26339, first using the GUI and then using

Code:

erase nvram && reboot


•Downgraded to 25697 and tried multiple factory resets via GUI and nvram
•Restored Asus official firmware for this device using ASUS RT-AC66U Firmware version 3.0.0.4.382_52745 and the 5G radio appears and is operational
•Switched back to DD-WRT 26339. 5G disappears. Even after factory resets via GUI & nvram telnet commands
•Added sleep 5; startstop lan to startup command script

So the 5G radio and hardware appears to be intact and working, but all of the published workarounds and fixes to bring the 5G radio back under old DD-WRT or modern DD-WRT releases don't work for me.

Anyone got any ideas?

p.s. The Asus firmware doesn't really support the client repeater feature. I need this device to connect to a 2.4Ghz network to create the bridge and then re-broadcast as a local AP on 5Ghz(the buildings are adjoining and I can't run physical ethernet to link them, but I have an outdoor WAP broadcasting that I can lock onto)

[kernel-panic69]

To the best of my understanding, you install r26339 and do a WPS button reset then upgrade to current release without doing any kind of reset. Your only other option is to flash FreshTomato.

[Per Yngve Berg]

Don't do a NVRAM ERASE on this model. It make the 5Ghz turn up as a 2.4Ghz

Load 26339 and reset

Then with newer builds, only reset with GUI.

[spaceghost]

OK - Thanks everyone. It was in fact doing the WPS reset method (power off, press and hold WPS button while powering on, release WPS button) on 26339 that was required. Nothing else would bring it back.

So I can jump straight to current release now (making sure to only reset via webgui)?

[Per Yngve Berg]

Yes.