configure minio in docker to use https

This is my docker-compose.yml:

version: '3.7'

services:
  minio:
    image: minio/minio
    command: server -C /etc/minio --address ":9000" --console-address ":9001" /data
    ports:
      - "9000:9000"
      - "9001:9001"
    environment:
      MINIO_ROOT_USER: minioadmin
      MINIO_ROOT_PASSWORD: minioadmin
    volumes:
      - minio:/data
      - /etc/minio:/root/.minio/
      - /etc/minio:/etc/minio/
      
volumes:
  minio:

ls -l /etc/minio/:

drwx------ 2 root root 4096 May 20 11:43 CAs
lrwxrwxrwx 1 root root   59 May 20 11:45 private.key -> /etc/letsencrypt/live/mydomain.com/privkey.pem
lrwxrwxrwx 1 root root   61 May 20 11:44 public.crt -> /etc/letsencrypt/live/mydomain.com/fullchain.pem

accessing via http works but https does not. I have no clue, what is wrong. Sadly the logs don't show anything and the docs are also not helping.

docker_compose.yml

networks:
  app-tier:
    driver: bridge


services:
  minio:
    image: minio/minio
    ports:
      - "9000:9000"
      - "9001:9001"
    networks:
      - app-tier
    volumes:
      - /data/minio:/data
    environment:
      MINIO_ROOT_USER: minioadmin
      MINIO_ROOT_PASSWORD: minioadmin
    command: server --console-address ":9001" /data
  nginx:
    image: nginx:latest
    container_name: 'nginx'
    hostname: 'nginx'
    ports:
      - "8443:8443" 
      - "8444:8444" 
    environment:
      - "VIRTUAL_HOST=minio.example.com"
      - "VIRTUAL_PORT=8443"
    networks:
      - app-tier
    volumes:
      - ./conf/app.conf:/etc/nginx/conf.d/default.conf:ro"
      - '/etc/letsencrypt/live/:/etc/letsencrypt/live/'
      - '/etc/letsencrypt/archive/:/etc/letsencrypt/archive/'
volumes:
  minio_storage: {}

app.conf should be placed in conf folder

upstream minio {
  server minio:9001;
  keepalive 15;
}
upstream minio_api {
  server minio:9000;
  keepalive 15;
}
server {
  listen 8443 ssl;
  server_name minio.example.com;
  ssl_certificate /etc/letsencrypt/live/minio.example.com/fullchain.pem;
  ssl_certificate_key /etc/letsencrypt/live/minio.example.com/privkey.pem;
  resolver 8.8.8.8;
  location / {
    proxy_pass http://minio;
    proxy_redirect off;
    proxy_buffering off;
    proxy_http_version 1.1;
    proxy_set_header Connection "Keep-Alive";
    proxy_set_header Proxy-Connection "Keep-Alive";
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";

    chunked_transfer_encoding off;

    proxy_set_header Host $http_host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;

  }
}
server {
  listen 8444 ssl;
  server_name minio.example.com;
  ssl_certificate /etc/letsencrypt/live/minio.example.com/fullchain.pem;
  ssl_certificate_key /etc/letsencrypt/live/minio.example.com/privkey.pem;
  resolver 8.8.8.8;
  location / {
    proxy_pass http://minio_api;
    proxy_redirect off;
    proxy_buffering off;
    proxy_http_version 1.1;
    proxy_set_header Connection "Keep-Alive";
    proxy_set_header Proxy-Connection "Keep-Alive";
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";

    chunked_transfer_encoding off;

    proxy_set_header Host $http_host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;

  }

}

Check the permissions for /etc/letsencrypt folder because the containers are running under non privileged user