Sketch: MQTT

First run

1. Push any of the buttons. Led indicator will start blinking and new wifi access point "Hugo_XXXXXX" will appear for 5 minutes.
2. Connect to the network from your phone or PC and open URL 10.10.10.1
3. There you will set your wifi credentials, broker credentials and topic + payload for each button. (OPTIONAL: If you use Home Assistant, just use suggested topics.)
4. (Optional) To potentially improve performance and battery life, you can add your router's gateway IP address and also pick a static IP for your remote. You will also have to set the static IP on your router.

MAC Address

Since version 1.3.1 you can find MAC address on config portal. Also, config portal SSID contains last 6 characters of the MAC address. This can help setting up static IP in your router.

Changing settings

Push and hold buttons 1 and 4 until the led indicator starts blinking. To shut down Config AP and resume normal function, just push any button.

Home Assistant

In case you use Home Assistant built-in MQTT broker, you can push and hold buttons 2 + 4 until the led lights up to register the device. It will appear in Settings / Integrations / MQTT: Mosquitto broker. This assumes you have MQTT and Mosquitto correctly set up beforehand.
Use suggested topics and payloads with Home Assistant.