Workaround for mt76: https://github.com/openwrt/mt76/issues/922

openwrt-mt76-disconnect-workaround.startup

(
disconnect() {
  local dev="$1" mac="$2"
  echo "$dev: disconnect $mac" > /dev/kmsg
  ubus call "hostapd.$dev" del_client "{'addr':'$mac','reason':8,'deauth':true,'ban_time':0}"
}

checkalive() {
  local dev="$1" mac="$2" inactive
  inactive="$(iw dev "$dev" station get "$mac" 2>/dev/null | sed -n 's/.*inactive time:[[:space:]]*\([0-9]*\).*/\1/p')"
  [ -z "$inactive" ] || [ "$inactive" -gt 60000 ] && disconnect "$dev" "$mac"
}

mt79_stuck_monitor() {
  local dev="$1"
  echo "$dev: watchdog [mt79-stuck-monitor]" > /dev/kmsg
  (
    while true; do
      sleep 10
      json="$(ubus call "hostapd.$dev" get_clients 2>/dev/null)" || continue
      while read -r mac; do
        [ -z "$mac" ] && continue
        tx="$(echo "$json" | jsonfilter -e "@.clients[\"$mac\"].airtime.tx")"
        rx="$(echo "$json" | jsonfilter -e "@.clients[\"$mac\"].airtime.rx")"
        [ -z "$tx" ] || [ -z "$rx" ] && continue
        txvar="tx_${mac//:/_}"
        rxvar="rx_${mac//:/_}"
        eval prev_tx=\${$txvar:-$tx}
        eval prev_rx=\${$rxvar:-$rx}
        eval $txvar=$tx
        eval $rxvar=$rx
        dtx=$((tx - prev_tx))
        drx=$((rx - prev_rx))
        if [ "$dtx" -eq 0 ] && [ "$drx" -eq 0 ]; then
          checkalive "$dev" "$mac"
        fi
      done <<EOF
$(echo "$json" | jsonfilter -e '@.clients' 2>/dev/null | grep -oE '([[:xdigit:]]{2}:){5}[[:xdigit:]]{2}')
EOF
    done
  ) &
}

# Ensure necessary services are up
sleep 40

# Start bogus-client monitoring for APs
for dev in $(iwinfo | awk '/phy[0-9]-ap[0-9]/ { print $1 }'); do
  mt79_stuck_monitor "$dev" &
done
)

If this is working you should see something like this:

[   54.071222] phy0-ap0: watchdog [mt79-stuck-monitor]
[   54.071519] phy1-ap0: watchdog [mt79-stuck-monitor]
[   54.071526] phy0-ap1: watchdog [mt79-stuck-monitor]
[   54.071886] phy1-ap1: watchdog [mt79-stuck-monitor]

With events following:

[  740.326456] phy0-ap1: disconnect c0:84:ff:32:d2:a4
[ 1466.660469] phy0-ap1: disconnect c0:84:ff:30:bb:fc