Since forever I've been using shared security settings for both 2Ghz & 5Ghz networks, i.e. the security settings set a single password to be used for both WPA2 & WPA3.

Unfortunately since upgrading to v7.16.1 (upgraded both ros as rb, didnt try 7.16.0), this shared security setting complete breaks 2Ghz wifi on the hAP AX2 as none of my 2Ghz-only devices is able to connect. Only after copying the security profiles to have a 2Ghz security setting without WPA3 and a 5Ghz security setting with WPA3 can my 2Ghz-only devices connect again.

Is this a known/expected issue? The shared security setting still seems to work on an AC3 device so it seems device/arch specific?

Note that the AX2 mentions that device does not support management protection when using a security profile with WPA3, but so those the AC3.

Unlikely.

I have a bunch of IoT devices REFUSING to connect to 2GHz when WPA3 is added to the mix.
I have a separate SSID ONLY using WPA2 (nothing else security-wise) and then they're happy.

What devices/arch are you using, `wifi-qcom` or `wifi-qcom-ac`?

As mentioned, similar 2Gz-only devices still connect fine on the AC3 but not on the AX2 since upgrading to v7.16.1. Both devices are fully upgraded to v7.16.1 and both were using shared security profiles with WPA2 & WPA3 since forever and it only causes issues on the AX2.

I have both wifi-qcom and wifi-qcom- ac.

Your ac3 is running wireless or wifi-qcom-ac ?
The former doesn't have WPA3 but I ask to be sure.

It's running wifi-qcom-ac indeed