[mt7996e][BPI-R4] Router becomes unreachable over wired Ethernet when 2.4 GHz AP client associates after mt76 2026.07.01~59676919 upgrade

Summary

After upgrading the OpenWrt SNAPSHOT Wi-Fi related kmods to mt76 2026.07.01~59676919-r1, my Banana Pi BPI-R4 becomes unreachable over wired Ethernet also as soon as a Wi-Fi client associates to the 2.4 GHz AP.

This is not just a Wi-Fi/hostapd failure. The wired LAN connection also dies, so it looks like either a kernel panic/hard lockup or a netdev/network stack hang triggered by the MT7996 driver path.

The issue disappears if I remove the upgraded Wi-Fi stack files from /overlay/upper and fall back to the versions from /rom.

Device

• Device: Banana Pi BPI-R4
• Target: mediatek/filogic
• OpenWrt: SNAPSHOT
• Kernel: 6.18.37
• Wi-Fi chip/driver: MT7996 / mt7996e

Bad packages

The issue appeared after upgrading to these packages:

kmod-cfg80211-6.18.37.6.18.26-r1
kmod-mac80211-6.18.37.6.18.26-r1
kmod-mt76-connac-6.18.37.2026.07.01~59676919-r1
kmod-mt76-core-6.18.37.2026.07.01~59676919-r1
kmod-mt7996-233-firmware-6.18.37.2026.07.01~59676919-r1
kmod-mt7996-firmware-6.18.37.2026.07.01~59676919-r1
kmod-mt7996-firmware-common-6.18.37.2026.07.01~59676919-r1
kmod-mt7996e-6.18.37.2026.07.01~59676919-r1

Symptom

With Wi-Fi disabled, the router boots and works normally over wired Ethernet.

If I enable only the 2.4 GHz radio, the AP comes up. As soon as a Wi-Fi client associates, the router becomes unreachable over wired Ethernet as well.

I have not yet confirmed whether this is a full kernel panic/hard lockup or a network stack/netdev hang, because I do not have a serial console log from the failure yet.

WED status

The issue reproduces with WED disabled.

/etc/modules.conf during the test:

options mt7996e wed_enable=0 sr_scene_detect=Y

So this does not look like a simple WED offload issue.

2.4 GHz radio config used during reproduction

config wifi-device 'radio0'
        option type 'mac80211'
        option path 'soc/11300000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0'
        option radio '0'
        option band '2g'
        option channel '1'
        option htmode 'HE40'
        option cell_density '0'
        option beacon_int '100'
        option log_level '1'
        option airtime_mode '1'
        option disabled '1'

Reproduction steps

1. Use Banana Pi BPI-R4 on OpenWrt SNAPSHOT, target mediatek/filogic, kernel 6.18.37.
2. Upgrade Wi-Fi related kmods to mt76 2026.07.01~59676919-r1.
3. Keep Wi-Fi disabled at boot.
4. Enable only the 2.4 GHz radio.
5. Connect one Wi-Fi client to the AP.
6. The router becomes unreachable over wired Ethernet.

Workaround

Removing the upgraded Wi-Fi stack files from /overlay/upper and falling back to the versions from /rom fixes the issue.

In other words:

old Wi-Fi stack from /rom: stable
upgraded Wi-Fi stack from overlay: router becomes unreachable when a client associates
overlay rollback: stable again

This looks like a regression in the upgraded MT76/MT7996/mac80211/cfg80211 stack.

Additional notes

A newer OpenWrt SNAPSHOT build is available, but the relevant MT76/MT7996 package versions still appear to be the same 2026.07.01~59676919-r1, so I do not see evidence yet that this issue has been fixed in the newer build.

Start by reproducing the failure on the Banana Pi BPI-R4 with the listed mt76 package versions and the 2.4 GHz configuration. Collect a serial console log to distinguish a kernel panic or hard lockup from a network stack or netdev hang, then compare the upgraded files in /overlay/upper with the stable versions in /rom. Done means a client can associate without making wired Ethernet unreachable.