Flask app running in docker container cannot be accessed: ERR_CONNECTION_RESET - docker

Question

I've found a lot of questions on this topic. Always the answer was to use the '0.0.0.0' IP-adress. But I'm already doing this and still I get the error.
So I'm running a docker compose file that runs a database and a flask front end. The dockerfile runs fine on my own computer but on the server in the cloud I am getting this error.
This code launches the application:
app.run(host="0.0.0.0", port=5000, ssl_context="adhoc", debug=cfg.app_debug_mode)
This is my docker compose file:
version: "3.8"
services:
app:
image: app_image #the beginning is the unique uri of my amazon qccount. Then follows the repository name (ratio) and then the tag of the image (app) https://docs.aws.amazon.com/AmazonECR/latest/userguide/docker-push-ecr-image.html
build: ./app
links:
- database
ports:
- "5000:5000"
environment:
AM_I_IN_A_DOCKER_CONTAINER: 'Yes'
CONFIG_NAME: 'config' #Name of the config file to use
database:
image: database_image
container_name: database
build: ./sql
restart: always
ports:
- "32000:32000"
environment:
MYSQL_ROOT_HOST: '%' #This allows the root user to access the database from any ip. For some reason amazon requires it.
MYSQL_ROOT_PASSWORD: 'zv2yRCt79AsGvz'
MYSQL_DATABASE: 'education'
volumes:
- ratio_volume:/var/lib/mysql #use a named volume for the database.
networks:
default:
name: my-network
volumes:
ratio_volume:
This is the docker file:
FROM python:3
RUN pip3 install --upgrade pip
WORKDIR /app
COPY . /app
RUN pip3 --no-cache-dir install -r requirements.txt
EXPOSE 5000
ENTRYPOINT ["python3"]
CMD ["/app/run.py"]
What am I doing wrong? The error is also not really helpful.. I am not getting any errors in the console, just the browser is complaining.