Nginx与websocket。通过websocket客户端发送任何数据时出现问题。 （110：连接超时）代理升级的连接时）

Question

我正在为我的项目使用网络套接字。我将python aiohttp用于服务器和客户端。在本地，通过ngrok，它运行完美。但是当我将它与Nginx一起放在服务器上时遇到了一些问题。

我已按照https://www.nginx.com/blog/websocket-nginx/

的指示进行了所有操作

map $http_upgrade $connection_upgrade {
     default upgrade;
     '' close;
        }
server {
        server_name example.com;
        listen 80;
        root /var/www/html;
        error_log /var/log/nginx/error.log debug;

        ...

        location /ws {
                include proxy_params;
                proxy_pass http://127.0.0.1:5402/ws;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection $connection_upgrade;
                proxy_set_header Host $host;
                }
}

当我连接到example.com/ws时，它可以按计划工作。我从Websocket服务器获得了下一个信息：

<Request GET /ws >
<WebSocketResponse Switching Protocols GET /ws > #HTTP 101 Switching Protocols

Nginx日志接下来显示给我：

    GET /ws HTTP/1.0
    Host: example.com
    X-Real-IP: ip
    X-Forwarded-For: ip
    X-Forwarded-Proto: http
    Upgrade: WebSocket
    Connection: upgrade
    Sec-WebSocket-Version: 13
    Sec-WebSocket-Key: 8LiAQ/oYM6PCsJ60brbQww==
    Accept: */*
    Accept-Encoding: gzip, deflate
    User-Agent: Python/3.7 aiohttp/3.6.2
    HTTP/1.1 101 Switching Protocols


    Server: nginx/1.16.1
    Date: Tue, 03 Mar 2020 16:59:49 GMT
    Content-Type: application/octet-stream
    Connection: upgrade
    Upgrade: websocket
    Sec-WebSocket-Accept: 7revI3OKdLXh8X/mtb/4h/3AVn8=

但是当我尝试通过客户端发送一些数据时，我的连接挂起了。我收到超时错误。我的后端服务器未收到任何请求。 Nginx记录下一条消息：

[info] 43386#43386: *1 upstream timed out (110: Connection timed out) while proxying upgraded connection, client: ip, server: example.com, request: "GET /ws HTTP/1.1", upstream: "http://127.0.0.1:5402/ws", host: "example.com"

PS，ngrok隧道服务器的后端日志消息（当所有按计划工作时）：

<Request GET /ws >
<WebSocketResponse Switching Protocols GET /ws > #HTTP 101 Switching Protocols
 WSMessage(type=<WSMsgType.TEXT: 1>, data=some_str)

您知道如何解决此问题吗？