Nginx Proxy Manger cannot connect to another server on the network

[Mephisto090]

Hej,

I have the following problem the Nginx Proxy Manager (NPM) cannot redirect to another server. (Network structure: See picture)

Network

This is not a problem in the same Docker Desktop system. The redirects work without any problems and I can call Paperless with paperless.domain.tdl.
However, if I now try to address the Apache server on the Raspberry Pi, I get a variety of errors depending on how I configure the subdomain in the NPM.
In the Fritzbox I forwarded ports 80 and 443 internally to 180 and 1443 to the Windows server (192.168.178.70) on which NPM is running.

Paperless works without any problems

502 Bad Gateway In this variant I get a 502 Bad Gateway

ERR_TOO_MANY_REDIRECTS In this variant I get a ERR_TOO_MANY_REDIRECTS

I tried it in Docker with Host or with the Bridge Network mode

Docker-Compose from NPM:

version: "3"
services:
  app:
    image: 'jc21/nginx-proxy-manager:latest'
    container_name: nginx
    restart: unless-stopped
    ports:
      # These ports are in format <host-port>:<container-port>
      - '180:80' # Public HTTP Port
      - '1443:443' # Public HTTPS Port
      - '81:81' # Admin Web Port
      # Add any other Stream port you want to expose
      # - '21:21' # FTP
    healthcheck:
      test: ["CMD", "/bin/check-health"]
      interval: 10s
      timeout: 3s
    environment:
      DB_MYSQL_HOST: "db"
      DB_MYSQL_PORT: 3306
      DB_MYSQL_USER: "user"
      DB_MYSQL_PASSWORD: "password"
      DB_MYSQL_NAME: "database"
      # Uncomment this if IPv6 is not enabled on your host
      DISABLE_IPV6: 'true'
      TZ: 'Europe/Berlin'
      CONTAINER_DEBUG: 'true'
    volumes:
      - ./data:/data
      - ./config:/config
      - letsencrypt:/etc/letsencrypt
      - logs:/data/logs
    depends_on:
      db:
        condition: service_healthy
    networks:
      - npm-proxy
      - default

  db:
    image: 'jc21/mariadb-aria:latest'
    restart: unless-stopped
    container_name: nginx-db
    environment:
      MYSQL_ROOT_PASSWORD: 'root_password'
      MYSQL_DATABASE: 'database'
      MYSQL_USER: 'user'
      MYSQL_PASSWORD: 'password'
    volumes:
      - ./data/mysql:/var/lib/mysql
    networks:
      - default
    healthcheck:
      test: ["CMD", "mysqladmin" ,"ping", "-h", "localhost"]
      timeout: 20s
      retries: 10
      
    
volumes:
  letsencrypt:
  logs:
  
networks:
  npm-proxy:
    name: npm-proxy
    driver: host # or with bridge
    attachable: true
    external: true

There is a ping and wget connection from the container to the Raspberry (192.168.178.44).

how can I successfully redirect the subdomain from the Nginx server to the Raspberry?

Thank you