Network is unreachable - upstream to Cloudflare

Dear Sir/Madam,

We would like to draw your attention to a recurring issue manifesting in the form of errors during requests. In the Nginx logs, we have observed error messages occurring during the “proxy_pass” invocation.

As an example, we would like to present the following entry:


2024/06/09 20:46:15 [error] 1635238#1635238: *157801 connect() to [2606:4700:3036::ac43:a530]:443 failed (101: Network is unreachable) while connecting to upstream, client:, server: xxx.xxxx.xx, request: “GET HTTP/1.1”, upstream: “https://[2606:4700:3036::ac43:a530]:443/”, host: “”, referrer: “https:///”

We are unable to isolate the problem to a specific domain. The IPv6 address mentioned in the error message originates from your end. The requested file exists and is accessible even when the IPv6 address in question is not utilized.

This issue occurs sporadically, sometimes more frequently than others, with the IPs constantly changing.

Could you provide us with insights into why your IPs become unresolvable during a request? How can we prevent this from happening and ensure smooth operation?

We appreciate your assistance in advance and remain

Yours faithfully,
Timo Frenzel

Can you share more information? As much of the following information as you can share is helpful.

1 Like

This topic was automatically closed 15 days after the last reply. New replies are no longer allowed.