连接到上游时出现 NGINX（111：连接被拒绝）错误

Question

我正在为 NGINX 设置配置，但不断收到以下错误：

8#8: *698 connect() failed (111: Connection refused) while connecting to upstream, client: <IP1>, server: <domain>, request: "GET /sito/wp-includes/wlwmanifest.xml HTTP/1.1", upstream: "uwsgi://<IP2>:9000", host: "<domain>"

我曾尝试过针对这里提出的不同问题的解决方案，但尚未找到解决方案。

Nginx 配置是

server {
    listen 443 ssl http2;
    server_name example.com  www.example.com;
    ssl_certificate /etc/nginx/certs/example.com.crt;
    ssl_certificate_key /etc/nginx/certs/example.com.key;

    location /static {
        alias /vol/static;
    }

    location / {
        uwsgi_pass ${APP_HOST}:${APP_PORT};
        include /etc/nginx/uwsgi_params;

        client_max_body_size 10M;
    }
}

server {
    listen 80;
    server_name example.com www.example.com;

    location / {
        return 301 https://example.com;
    }

}

Nginx Dockerfile：

FROM nginx:1.21.3
LABEL maintainer="example"

COPY ./default.conf.tpl /etc/nginx/default.conf.tpl
COPY ./uwsgi_params /etc/nginx/uwsgi_params
COPY ./certs/example.com.crt /etc/nginx/certs/
COPY ./certs/example.com.key /etc/nginx/certs/
COPY ./certs/example.com.pem /etc/nginx/certs/
COPY ./run.sh /run.sh

ENV APP_HOST=app
ENV APP_PORT=9000

# USER root

RUN mkdir -p /vol/static && \
    chmod 755 /vol/static && \
    touch /etc/nginx/conf.d/default.conf && \
    chown nginx:nginx /etc/nginx/conf.d/default.conf && \
    chmod +x /run.sh && \
    chmod +r /etc/nginx/certs/example.com.crt && \
    chmod +r /etc/nginx/certs/example.com.pem && \
    chmod +r /etc/nginx/certs/example.com.key

VOLUME /vol/static

# USER nginx

CMD ["/run.sh"]

Docker 组成：

version: "3.3"

services:
    app:
        build:
            context: .
        restart: always
        volumes:
            - static-data:/vol/web
        environment:
            - *some environment variables*

    proxy:
        build:
            context: ./proxy
        restart: always
        depends_on:
            - app
        ports:
            - "80:80"
            - "443:443"
        volumes:
            - static-data:/vol/static
            - ./proxy/certs:/etc/nginx/certs


volumes:
    static-data:

这里提到的应用程序是一个 Django Web 应用程序。

如果你们能帮助我找到这个问题那就太好了。