几分钟后，Kurento websocket连接关闭

Question

我正在使用前端的nginx在kurento上配置SSL。但我的webSocket连接在4分钟后中断。这是我在启用网站的内容中的nginix conf。

server {

    listen 443;

    #host name to respond to
    server_name ****.com;
    # your SSL configuration
    ssl on;
    ssl_certificate /etc/letsencrypt/live/****.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/****.com/privkey.pem;

    location / {

        # redirect all HTTP traffic to localhost:8080
        proxy_pass https://localhost:8443;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_connect_timeout 86400s;
        proxy_read_timeout 86400s;
        keepalive_timeout  0;
        # WebSocket support (nginx 1.4)
        proxy_http_version 1.1;
       proxy_set_header Upgrade $http_upgrade;
       proxy_set_header Connection "upgrade";
    }
}