How to resolve Http Load Balancing Error 1003 on cloudflare dns?

Question

SSL/TLS encryption mode on Cloudflare side is on "flexible" status (https on)

server side setting on third server is:

upstream backend {
  server domain1.com;
  server domain2.com;
}
server {
  listen 80;
  location / {
    proxy_pass http://backend;
 }

Error message is: Error 1003 Direct IP access not allowed

Cloudflare explains: Error 1003 Access Denied: Direct IP Access Not Allowed Common cause A client or browser directly accesses a Cloudflare IP address. Resolution Browse to the website domain name in your URL instead of the Cloudflare IP address.

Answer 1

I resolved this problem with set proxy to the header

proxy_set_header Host www.domain.io;