Nighthawk R6700 5G radio not working after firmware upgrade

[Ultra-Giraffe]

Netgear Nighthawk R6700 that I just upgraded to firmware V1.0.1.20_10.0.3.  It seems to have killed the 5G radio.  I have confirmed with a wifi environment analysis utility (Mac OS "WiFi Explorer" application) that the 5G wifi zone no longer exists.  2.4G radio and signal are fine.  (It's not a signal strength problem because my wifi environment is not crowded and the 5G signal:noise ratio was somethig line 50dB before it went away.  Normally the 5G zone shows up very strong.)

Configuration is unchanged to that which worked before the upgrade.  Router runs in AP mode (not router mode) and is hard-wired to another Netgear router (C7000-100NAS) that is also my cable modem interface.  All routers and wifi AP's have unique wifi zone names.  

Things I have tried:

-- rebooting the router in software

-- power-disconnecting the router for 30+ seconds

-- reverting to factory settings, both via web interface and via the recessed hard reset button (held for 7 seconds)

-- disabling the radio under "advanced wifi settings", applying changes, then re-enabling it again

-- enabling smart merge of 2.4G and 5G zones, applying changes, then disabling it again

-- changing radio signal strength from 100% to 50%, applying changes, then restoring full strength again

-- changing the radio's broadcast channel

-- disabling and re-enabling wifi with the LED-illuminated hard button on the right front corner of the router case

I'm at a loss for what to try next.  Any thoughts or help would be greatly appreciated.

[JamesGL · Accepted solution]

Hi Ultra-Giraffe,

Try to observe the 5GHz connection. If it is stable now, try to reload the latest firmware. Reset and reconfigure. If it is not stable with the current firmware that is loaded on the router, I would suggest contacting support for possible replacement. Check with them the warranty of your device.

[Ultra-Giraffe]

I should add that the router web interface shows the 5G wifi zone as enabled and working normally.

[JamesGL]

Hi Ultra-Giraffe,

Try to reload the previous firmware and check if the same problem.

https://kb.netgear.com/000036748/R6700-Firmware-Version-1-0-1-16

[Ultra-Giraffe]

Thanks for the suggestion but it didn't help.  I also tried toggling the SSID Broadcast and changing the network name.  Neither of these worked either.  The router still thinks the 5GHz band is working normally, but my wifi sniffer application still shows no 5G zone and it doesn't show up on any of my various devices (various Mac OS computers and iPads/iPhones).

[Ultra-Giraffe]

So today, 24 hours after downgrading to version xxx.16 as you recommended, the 5G wifi zone has come back.  I'm not sure why it took so long to reappear and I'm not convinced it was related to the downgrade.  Is it possble this is just an intermittent hardware failure?  Any thoughts on additional things to check (hardware or software) would be appreciated.

Thanks in advance.

[JamesGL · Accepted solution]

Hi Ultra-Giraffe,

Try to observe the 5GHz connection. If it is stable now, try to reload the latest firmware. Reset and reconfigure. If it is not stable with the current firmware that is loaded on the router, I would suggest contacting support for possible replacement. Check with them the warranty of your device.

[JamesGL]

Hi Ultra-Giraffe,

We’d greatly appreciate hearing your feedback letting us know if you need further assistance.