Docker compose doesn't work with mqtt

The following configuration results in a tcp socket error for mqtt.

find3server:
  container_name: find3server
  restart: unless-stopped
  image: schollz/find3
  environment:
    - MQTT_ADMIN=admin
    - MQTT_PASS=mypass
    - MQTT_SERVER='localhost:1883'
  volumes:
    - /home/USER/find3server:/data
  ports:
    - "11883:1883"
    - "8003:8003"

I have no idea why. It should work. I think its a docker-compose error because regular Docker works just fine, e.g.:

docker run -p 1884:1883 -p 8005:8003 \
	-v /home/$USER/FIND_DATA:/data \
    -e MQTT_ADMIN=ADMIN \
    -e MQTT_PASS=PASSWORD \
    -e MQTT_SERVER='localhost:1883' \
	-e MQTT_EXTERNAL='your public IP' \
	-e MQTT_PORT=1884 \
	--name find3server -d -t schollz/find3

will work no problem.