MacBook Air M2 on macOS 27.2 cannot connect to UniFi 5 GHz Wi-Fi (error -3912)

MacBook Air M2 on macOS 27.2 can’t connect to UniFi Wi‑Fi on 5 GHz (error -3912). 2.4 GHz works.

Since updating my MacBook Air (M2) to macOS 27.2, it can’t hold a 5 GHz connection to my UniFi Dream Router 7 (UDR7). iPhones and other non-Apple devices have had no issue with wired or wireless connection on the same network and on other wireless networks and VLANs through the same gateway.

What happens:

On my main WPA2/WPA3 (transition mode) network, the Mac connects briefly on 5 GHz and then drops. Its Wi‑Fi log shows WiFiNetworkDisconnectReason = INVALID_AKMS while using WPA3‑SAE. It then falls back to a distant 2.4 GHz access point at poor signal, so the connection keeps dropping.
Once the Mac has joined that network with WPA3, it won’t connect to it with WPA2 (“incorrect security type”).
I created a separate WPA2‑only, 5 GHz‑only network (PMF off, BSS Transition off, MLO off). It worked at first, then after a router restart the Mac couldn’t rejoin. The password prompt comes back immediately, and networksetup -setairportnetwork fails with error -3912. A brand‑new WPA2 network on 5 GHz fails the same way.
The same new WPA2 network on 2.4 GHz connects immediately and is stable (0% loss, about 12 ms to the gateway). The Mac also works fine on an iPhone hotspot’s 5 GHz.

Already tried: restarting the router and the Mac, forgetting and re‑adding networks, entering the password manually and from Terminal, turning off iCloud Keychain sync, and disabling AWDL. Keychain has no stale entries for these networks. This is the latest macOS available to me.

Setup: UDR7 (firmware 5.1.35) plus a U7‑IW access point. 5 GHz on channel 153 at 80 MHz.

Is anyone else seeing 5 GHz problems with UniFi Wi‑Fi 7 gear since 27.2? I’ll be testing another MacBook Air M2 on the previous macOS tonight to confirm it’s the update.

Post was created with help from Claude which assisted with troubleshooting.

Edit: Apple attributes MacBook Pro 13" OS X 10.11 - Ignore that, it's an old device that's been decommissioned. I'm not sure why it's still showing up on here.

Posted on Nov 10, 2026 8:44 AM

1 reply

kaz-k

Level 9 (53,902 points)

Nov 10, 2026 10:09 AM in response to 9POINT5

Hi,

macOS Wi-Fi connection error -3912 means kCWChallengeFailureErr (Challenge Fail Error) in internal code, indicating that the authentication handshake between Mac and router (AP) is not completed successfully.

If this error occurs in the combination of a 5 GHz UniFi environment and a Mac with Apple Silicon (M series), the main cause is PMF (PMF: Protected Management Frame), WPA3 security, or **fast roaming (802.11r)** standard conflict.

Try following methods.

1. Change the settings of PMF and WPA3 on the UniFi side

M-series Macs may fail specific WPA3/PMF implementations and handshakes for UniFi.

How to set up: Log in to the UniFi Network Controller and open the Settings ➔ WiFi ➔ the corresponding SSID editing screen.

PMF (Protected Management Frames): If it is "Required", change it to "Optional" or temporarily "Disabled" Set to.

Security Protocol: If it is dedicated to WPA3, please check if you can switch to "WPA2/WPA3" migration mode or temporarily drop it to "WPA2-only" for verification and connect.

2. Disable high-speed roaming (802.11r)

When 802.11r (Fast Roaming) is enabled, there are cases where error -3912 is triggered due to a shift in the challenge response timing of the authentication.

How to set: Uncheck "Fast Roaming" in the same UniFi's SSID settings and disable it.

After changing the settings on the UniFi side, you will need to clear the old credentials cached on your Mac.

Open System Settings ➔ Wi-Fi on your Mac.

Details next to the corresponding UniFi SSID... Click and select "Delete this network".

Turn off Wi-Fi once, wait about 10 seconds, and turn it on again.

Re-enter the password to reconnect to the 5 GHz SSID.

4. Check the channel width and DFS channel (if it is not improved)

If the channel width of the 5 GHz band is set to a broadband such as "160MHz", or if the "DFS channel" is used, the timing of the radio wave is likely to fail the challenge. On the UniFi side, fix the channel width in the 5 GHz band to "40MHz" or "80MHz" and manually allocate channels other than DFS (such as 36-48).