How to defeat nodejs error?

Question

Node.js

Site on Strapi , content blocks stopped working (server on Nodejs)

Instead of them, an error is displayed

Error: {"graphQLErrors":[],"networkError":{},"message":"Network error: Failed to fetch"}

Log errors are coming

2020/10/21 06:43:36 [error] 358#358: *49 connect() failed (111: Connection refused) while connecting to upstream, client: 62.115.15.146, server: , request: "GET / HTTP/1.1", upstream: "http://[::1]:3000/", host: "site.com"
2020/10/21 06:43:36 [error] 358#358: *49 connect() failed (111: Connection refused) while connecting to upstream, client: 62.115.15.146, server: , request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:3000/", host: "site.com"

After restarting the server, it stopped working, launched

So that it launched the application, the site itself began to work, but the error above cut off all content