[程序员] nginx 反代 websocket，为什么被代理端写入错误 write: broken pipe ？

客户端能与 nginx 握手成功，但接收不到数据，难道是 nginx 这边关闭了被代理端连接？ 搞了快一天，Google 也搜不到，使劲浑身解数还是没辙，

upstream target {
        server xxx.xxx.xxx.xxx:8080;
}
 location /wss {
        proxy_pass http://target/ws;
        proxy_http_version 1.1;
        proxy_set_header Upgrade websocket;
        proxy_set_header Connection "Upgrade";
        proxy_redirect off;
        proxy_cache_bypass $http_upgrade;
    	proxy_set_header Host $host;
    	proxy_set_header X-Real-IP $remote_addr;
    	proxy_set_header X-Forwarded-For $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    	proxy_buffering off;
    	proxy_set_header X-Forwarded-Host $server_name;
        proxy_set_header Access-Control-Allow-Origin *;
        proxy_set_header X-NginX-Proxy true;
        proxy_set_header Upgrade $http_upgrade;
	    proxy_set_header Connection $connection_upgrade;
	    gzip off;
	    proxy_set_header X-Forwarded-Ssl on;
	    proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Frame-Options SAMEORIGIN;
        proxy_read_timeout 5d;
        proxy_send_timeout 5d;
        proxy_connect_timeout 5d;
        send_timeout 5ds;
        fastcgi_connect_timeout 5d;  
        fastcgi_read_timeout 5d;   
        fastcgi_send_timeout 5d;   
    }

然后 golang 这边服务端写入时的错误为

ws written err: write tcp xxx:8080->xxx:53376: write: broken pipe