How to set this system up install:- 1- Mosquitto MQTT Broker 2- MongoDB server 3- CP210x Windows Drivers (for esp32 USB connection) 3- MQTT Explorer (optional) 4- MongoDB Compass (optional) 5- Arduino IDE & VSCode (optional for code review and/or editing)

You need to edit the mosquitto.conf file in the Mosquitto installaion path, add 'listener 1883 allow_anonymous true' to make the broker listen on the 1883 port.