Nginx：从上游读取响应头时，recv() 失败（104：对端重置连接）

Question

当我一次上传多张图片时，我的网站就会崩溃，上传完成后网站就会恢复。有人能帮我解决这个问题吗？

Nginx 错误日志： 2020/03/19 04:04:29 [error] 6#6: *5085 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 162.158.165.196, server: iwallpaper.xyz, request: "POST /wp-admin/async-upload.php HTTP/1.1", upstream: "fastcgi://172.26.0.3:9000", host: "iwallpaper.xyz", referrer: "https://iwallpaper.xyz/wp-admin/upload.php"

Server: Nginx (by EasyEngine)
CMS: WordPress (by EasyEngine)
OS: Ubuntu 18.04 x64
Ram: 1024 MB
CPU: 1 vCore

PHP信息：https://iwallpaper.xyz/phpinfo.php

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