Zyxel Nebula 19.10 Update: 2.4GHz Radio Mode Change for WiFi 7 Access Points

Zyxel_Lynn

As part of the latest updates in the Zyxel Nebula 19.10 release, one of the key enhancements involves a fundamental change to the 2.4GHz radio mode configuration on our WiFi 7 (11BE) access points. This article breaks down the reasoning, implications, and what users can expect after upgrading to firmware version 7.20.

Why the Change Was Necessary

Despite leveraging transition mode (which broadcasts both WPA2 and WPA3 security profiles simultaneously), many legacy clients still face challenges connecting to WiFi 7 APs. These clients struggle to transition between WPA3 and WPA2, and Enhanced Open is not supported in transition mode under 11BE. As a result, a segment of older devices remains unable to connect reliably to the network.

The Solution: Switching 2.4GHz to 11AX

To address this, Zyxel has changed the default 2.4GHz radio mode from 11BE to 11AX on WiFi 7 APs. This shift serves a dual purpose:

(1) Improves compatibility with older security standards (e.g., WPA2)

(2) Avoids enabling MLO (Multi-Link Operation), which is mandatory in 11BE and

restricts the use of older methods.

Summary Before and After Firmware 7.20

Firmware Version	2.4GHz Default Radio Mode
Pre-7.20	11BE
7.20 and Later	11AX

Think of the 2.4GHz band as the "radio of last resort", optimized for legacy clients with limited support for newer technologies.

Impact on Different Deployment Modes

Standalone Mode

● Before 7.20: Factory reset APs revert to 11BE on 2.4GHz.

● After 7.20: Factory reset sets the radio mode to 11AX.

Nebula Cloud-Managed Mode

● 2.4GHz radio mode is changed from Auto to Auto up to 11AX.

● Device-level configurations reflect this change while retaining existing settings such

as channel width, DCS schedule, and DFS/client awareness.

Controller-Managed (ZLD) Mode

● Upgrading the ZLD firewall to firmware 5.40 forces the 2.4GHz radio from 11BE to

11AX.

● However, all other 2.4GHz settings revert to factory defaults—an unintentional

behavior currently under review.

USG Flex H-Series (UOS)

● GUI does not yet support manual configuration of radio settings.

● Upon upgrading APs to 7.20, 2.4GHz radios using 11BE will automatically switch to

11AX.

Important: Settings like channel width should remain unchanged in most modes—except for Controller-Managed Mode, where full reset occurs.

Considerations for WPA3 and Legacy Devices

While switching to 11AX enables support for older security protocols, WPA3 still requires 802.11ax or newer clients. Therefore, even under 11AX mode, WPA3 will not be usable by older legacy clients.

Known Issues and Workarounds

ZLD Controller Firmware Reset

● Issue: Upgrading to firmware 5.40 resets all 2.4GHz settings to default.

● Status: Not documented in original spec; currently treated as a known issue.

MAC Authentication and MLO

● Current Status:

Not officially confirmed. Under investigation.

For those managing WiFi 7 deployments or planning firmware upgrades, it’s important to:

1. Audit your current 2.4GHz configurations.
2. Understand how the firmware 7.20 upgrade will impact default settings.
3. Be mindful of the behavior differences between standalone, cloud, and controller modes.
4. Plan around known issues (e.g., ZLD reset bug).

Stay tuned for more updates as Zyxel continues refining support for WiFi 7 features and ensuring robust legacy client compatibility.