Use Home Assistant to keep Flint 2 (GL-MT6000) cool

When I got my GL-MT6000 (Flint 2) router, it quickly became obvious that it likes to run warm, especially under load.

Rather than just letting it sit on a shelf getting hot, I decided to combine a 3D-printed stand with active cooling and Home Assistant automation to keep it in check.

In this guide, I’ll show you how to build the stand, hook up fans with an ESP32 (via ESPHome), and bring everything into Home Assistant so you can monitor temperature and adjust fan speed automatically.

Making the Stand

In order to make the stand, you’ll need to download the STL files from https://makerworld.com/en/models/2110927-router-dual-fan-stand and 3D print the required parts.

As well as the 3D printed parts, you’ll need the following:

2x 80mm fans
Insect mesh, to try to reduce the amount of dust pushed towards the router
1x Adafruit HUZZAH32 – ESP32 Breakout Board ( for ESPHome)
1x MT3608 DC-DC
1x USB Type C 3.1 Female Socket DIY Serial Basic Breakout Female Connector
1x 10V, 470uF capacitor + 1x 16V, 470uF capacitor
1x A03400 mosfet for PWM control

Once you’ve printed the required parts, assemble them.

Building the controller

For the controller, you’ll need to make the following connections.

Connect the USB-C PCB with the 10V, 470uF capacitor
Power the ESP32 directly from the USB-C using the V+ pin, as that can take up to 6V
Connect the USB-C PCB with the VI+ and VI- on the MT3608 DC-DC
Connect the VO+ and VO- with the 16V, 470uF capacitor
Connecting the Fan
- VO+ with the fan V
- D(Drain) from the MOSFET with Fan GND
Connecting the MOSFET
- ESP32 GPIO21 — Gate
- Gate — 100kΩ — GND (pulldown)
- MOSFET Source — GND (common with ESP32)
- MOSFET Drain — Fan(-)

ESPHome YAML Code

YAML

esphome:
  name: router-fan

esp32:
  board: featheresp32
  framework:
    type: esp-idf

logger:
api:
ota:
  - platform: esphome
    password: ""

wifi:
  ssid: "WIFI_SSID"
  password: "WIFI_PASSWORD"

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "Router Fan Control"
    password: "SSID_PW"


# -------------------------------
# PWM OUTPUT (Fan Speed Control)
# -------------------------------
output:
  - platform: ledc
    pin: GPIO21
    id: router_fan_pwm
    frequency: 25000 Hz

# -------------------------------
# Home Assistant Fan Entity
# -------------------------------
fan:
  - platform: speed
    name: "Speed Control"
    output: router_fan_pwm
    speed_count: 100
    id: router_fan

Sending the data from Flint 2 (GL-MT6000) to your Home Assistant

Required Libraries:

mosquitto-client-nossl
nano-full

Creating the required Files.

/usr/bin/mqtt_sensors.sh

Bash/Shell

#!/bin/sh

MQTT_HOST="192.168.8.123"
MQTT_PORT="1883"
MQTT_USER="mqtt_user"
MQTT_PASS="mqtt_passwrd"

DEVICE_ID="GL-MT6000"
INTERVAL=5

BASE_TOPIC="home/$DEVICE_ID"
DISCOVERY_PREFIX="homeassistant"

# ---------------- HELPERS ----------------
publish_discovery() {
    mosquitto_pub -h "$MQTT_HOST" -p "$MQTT_PORT" \
        -u "$MQTT_USER" -P "$MQTT_PASS" \
        -t "$1" -r -m "$2"
}

publish_value() {
    mosquitto_pub -h "$MQTT_HOST" -p "$MQTT_PORT" \
        -u "$MQTT_USER" -P "$MQTT_PASS" \
        -t "$1" -r -m "$2"
}

DEVICE_JSON="\"device\":{
  \"identifiers\":[\"$DEVICE_ID\"],
  \"name\":\"$DEVICE_ID\",
  \"manufacturer\":\"GL.iNet\",
  \"model\":\"GL-MT6000\"
}"

# ---------------- HA DISCOVERY ----------------
publish_discovery "$DISCOVERY_PREFIX/sensor/${DEVICE_ID}_temperature/config" "{
  \"name\":\"CPU Temperature\",
  \"state_topic\":\"$BASE_TOPIC/temperature\",
  \"unit_of_measurement\":\"°C\",
  \"device_class\":\"temperature\",
  \"unique_id\":\"${DEVICE_ID}_temperature\",
  $DEVICE_JSON
}"

publish_discovery "$DISCOVERY_PREFIX/sensor/${DEVICE_ID}_cpu/config" "{
  \"name\":\"CPU Load\",
  \"state_topic\":\"$BASE_TOPIC/cpu\",
  \"unit_of_measurement\":\"%\",
  \"icon\":\"mdi:cpu-64-bit\",
  \"unique_id\":\"${DEVICE_ID}_cpu\",
  $DEVICE_JSON
}"

publish_discovery "$DISCOVERY_PREFIX/sensor/${DEVICE_ID}_memory/config" "{
  \"name\":\"Memory Usage\",
  \"state_topic\":\"$BASE_TOPIC/memory\",
  \"unit_of_measurement\":\"%\",
  \"icon\":\"mdi:memory\",
  \"unique_id\":\"${DEVICE_ID}_memory\",
  $DEVICE_JSON
}"

# ---------------- MAIN LOOP ----------------
while true; do
    # CPU Temperature
    RAW_TEMP=$(cat /sys/class/thermal/thermal_zone0/temp 2>/dev/null)
    [ -z "$RAW_TEMP" ] && RAW_TEMP=0
    TEMP=$(awk "BEGIN {printf \"%.2f\", $RAW_TEMP/1000}")

    # CPU Load (scaled by 65536)
    LOAD=$(ubus call system info | jsonfilter -e '@.load[0]')
    [ -z "$LOAD" ] && LOAD=0
    CPU=$(awk "BEGIN {printf \"%.2f\", $LOAD/65536*100}")

    # Memory %
    MEM_TOTAL=$(awk '/MemTotal/ {print $2}' /proc/meminfo 2>/dev/null)
    MEM_TOTAL=${MEM_TOTAL:-0}
    MEM_AVAILABLE=$(awk '/MemAvailable/ {print $2}' /proc/meminfo 2>/dev/null)
    MEM_AVAILABLE=${MEM_AVAILABLE:-0}
    MEM_USED=$((MEM_TOTAL-MEM_AVAILABLE))
    MEM_PERC=$(awk "BEGIN {printf \"%.2f\", $MEM_USED*100/$MEM_TOTAL}")

    # ---------------- PUBLISH ----------------
    publish_value "$BASE_TOPIC/temperature" "$TEMP"
    publish_value "$BASE_TOPIC/cpu" "$CPU"
    publish_value "$BASE_TOPIC/memory" "$MEM_PERC"

    sleep "$INTERVAL"
done

Once you have the file, use the following command to make it executable.

Bash/Shell

chmod +x /usr/bin/mqtt_sensors.sh

Create an init.d script to make it run as a service

/etc/init.d/mqtt_sensors

Bash/Shell

#!/bin/sh /etc/rc.common
# This service will run the mqtt_sensors script

START=99
STOP=10

start() {
    echo "Starting MQTT Sensors Service..."
    /usr/bin/mqtt_sensors.sh &
    # Save the PID of the script to a file so we can kill it later
    echo $! > /var/run/mqtt_sensors.pid
}

stop() {
    echo "Stopping MQTT Sensors Service..."
    # Get the PID of the running process
    PID=$(cat /var/run/mqtt_sensors.pid)
    kill $PID
    rm /var/run/mqtt_sensors.pid
}

restart() {
    stop
    start
}

# Ensure the service runs after reboot
boot() {
    start
}

Once you have the file, use the following command to make it executable.

Bash/Shell

chmod +x /etc/init.d/mqtt_sensors

Commands:

Bash/Shell

# Enable the service to start at boot
/etc/init.d/mqtt_sensors enable

# Disable auto-start on boot
/etc/init.d/mqtt_sensors disable

# Start, stop, or restart the service
/etc/init.d/mqtt_sensors start
/etc/init.d/mqtt_sensors stop
/etc/init.d/mqtt_sensors restart

# Check the symbolic links in /etc/rc.d/
ls -l /etc/rc.d/ | grep mqtt_sensors

# Find the current PID
ps | grep mqtt_sensors | grep -v grep

# Get the current memory usage
cat /proc/PID_ID/status | grep -E 'VmRSS|VmSize'

Home Assistant Automation

YAML

- id: router_fan_linear_control
  alias: Router Fan Linear Control
  description: "Linear fan speed control based on CPU temperature"
  trigger:
    platform: state
    entity_id: sensor.gl_mt6000_cpu_temperature
  action:
    service: fan.set_percentage
    target:
      entity_id: fan.router_fan_speed_control
    data:
      percentage: >
        {% set temp = states('sensor.gl_mt6000_cpu_temperature')|float %}
        {% set min_temp = 32 %}
        {% set max_temp = 65 %}
        {% set min_speed = 15 %}
        {% set max_speed = 100 %}
        {% if temp <= min_temp %}
          {{ min_speed }}
        {% elif temp >= max_temp %}
          {{ max_speed }}
        {% else %}
          {{ (min_speed + (temp - min_temp)*(max_speed - min_speed)/(max_temp - min_temp)) | round(0) }}
        {% endif %}