MT7628: Clients keep disconnecting. #169

Issue #169 remains unresolved.

I have a HC5661A using MT7628. I've just test the latest commit e2eedc9 and it's very unstable.
I connect my xperia phone to the wifi and it keeps disconnected around every 10 minutes. And the log keeps showing:

WPA: group key handshake completed (RSN)

I google for a solution and I added the followings to /etc/config/wireless

option wmm '0'
option wpa_group_rekey '0'
option wpa_pair_rekey '0'
option wpa_master_rekey '0'

Things become better. But after 18-20 hours, clients disconnect again and the AP disappears from the air. I reference to the log and it shows:

hostapd: wlan0: STA xx:xx:xx:xx:xx:xx IEEE 802.11: disconnected due to excessive missing ACKs

I asked google for help again and added the following line to /etc/config/wireless:

option disassoc_low_ack '0'

After a few days testing, clients also keep disconnected, the log did not show something related to ACKs but:

hostapd: wlan0: STA 00:00:00:00:00:02 IEEE 802.11: disassociated due to inactivity
daemon.info hostapd: wlan0: STA 00:00:00:00:00:02 IEEE 802.11: deauthenticated due to inactivity (timer DEAUTH/REMOVE)
daemon.notice hostapd: wlan0: AP-STA-DISCONNECTED xx:xx:xx:xx:xx:xx

BTW, when clients disconnected, only rebooting recover the AP.

The full /etc/config/wireless:

config wifi-device 'radio0'
        option type 'mac80211'
        option channel '11'
        option hwmode '11g'
        option path 'platform/10300000.wmac'
        option htmode 'HT20'
        option country '00'
        option legacy_rates '1'

config wifi-iface 'default_radio0'
        option device 'radio0'
        option network 'lan'
        option mode 'ap'
        option ssid 'LEDE'
        option wmm '0'
        option encryption 'psk-mixed'
        option key 'keep it secret'
        option wpa_group_rekey '0'
        option wpa_pair_rekey '0'
        option wpa_master_rekey '0'
        option disassoc_low_ack '0'

Start with the MT7628/mac80211 driver path and the supplied /etc/config/wireless settings, then reproduce the periodic client disconnects while collecting the hostapd messages shown in the report. Compare the group-key, missing-ACK, and inactivity events to determine why the AP requires a reboot; done means clients remain connected and the AP recovers without rebooting.