I am trying to connect a mqtt client and the broker. The problem is that they use the same port and docker says that the port is in use.

Connection is refused. This is my dockerfile and docker compose file.

services:
  mosquitto:
    image: eclipse-mosquitto:2
    container_name: mosquitto
    ports:
      - "1883:1883"
      - "9001:9001"
    volumes:
      - ./mosquitto.conf:/mosquitto/config/mosquitto.conf
      - ./mosquitto/data:/mosquitto/data
      - ./mosquitto/log:/mosquitto/log
    networks:
      - mqtt_network
  modbus:
    build:
      context: .
      dockerfile: Dockerfile
    depends_on:
      - mosquitto
    container_name: modbus
    devices:
      - /dev/ttyUSB0:/dev/ttyUSB0
    networks:
      - mqtt_network
networks:
  mqtt_network:
    driver: bridge

FROM python:3.12-slim

WORKDIR /app

ARG VERSION=1.0.0
COPY ./dist/modbus-${VERSION}-py3-none-any.whl .

RUN pip install --no-cache-dir modbus-${VERSION}-py3-none-any.whl

RUN mkdir -p /app/logs

EXPOSE 1883

CMD ["modbus"]

persistence true
persistence_location /mosquitto/data/
log_dest file /mosquitto/log/mosquitto.log
listener 1883
allow_anonymous true