Timeout during connect (likely firewall problem) SSL / TLS Origin: Network Last updated 4 Nov 2026

Let's Encrypt: Fetching http://example.com/.well-known/acme-challenge/token: Timeout during connect (likely firewall problem)

The ACME validation server could not reach your server on port 80 within the timeout.

Exact message you may see Timeout during connect (likely firewall problem)Fetching http://example.com/.well-known/acme-challenge: Timeout during connectConnection refused acme challengeFetching http://example.com/.well-known/acme-challenge/: Connection refusedTimeout after connect (your server may be slow or overloaded)
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Seen on: SSL Linux

Meaning

Let's Encrypt validates from several public IPs. The request must reach your web server on port 80 from anywhere. Open the firewall/security group, ensure the server or CDN accepts HTTP, check geo/IP blocking, and that DNS points to the right IP. Cloudflare "Always Use HTTPS" is fine, a blocking WAF rule is not.

Common causes

  • Port 80 blocked by firewall/security group
  • DNS points to a different IP
  • Geo-blocking or WAF blocking validators
  • Server behind NAT without port forward
  • Web server stopped

⚡ Quick fix

  1. Open inbound TCP 80
  2. Verify curl -I http://example.com/.well-known/acme-challenge/test from outside
  3. Allow validator IPs or disable geo-blocks during issuance

Detailed fix by platform

Linux

  1. sudo ss -ltnp | grep ':80 ' and curl -I http://example.com/.well-known/acme-challenge/test from another network

How to diagnose

  1. Port — 80 open externally?
  2. DNS — Points here?
  3. WAF — Blocking?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: Network. Errors that are often confused with or caused by this one (click to open):

1005 — Cloudflare Error 1005: Access denied — The owner of this website has banned the autonomous system number (ASN) your IP address is in (Cloudflare)10051006 — Cloudflare Error 1006 / 1007 / 1008: Access denied — Your IP address has been banned (Cloudflare)10061012 — Cloudflare Error 1012: Access denied (Cloudflare)10121020 — Cloudflare Error 1020: Access Denied (Cloudflare)1020AH01909: server certificate does NOT include an ID which matches the server name — Apache: [ssl:warn] AH01909: example.com:443:0 server certificate does NOT include an ID which matches the server name (SSL / TLS)AH01909: server certi…CAA record forbids issuance — Let's Encrypt/CA: CAA record for example.com prevents issuance (SSL / TLS)CAA record forbids is…certificate does not have a private key (IIS) — Windows/IIS: A specified logon session does not exist / The certificate does not have a private key associated with it (SSL / TLS)certificate does not …Certificate pinning failure! — Android/OkHttp: javax.net.ssl.SSLPeerUnverifiedException: Certificate pinning failure! Peer certificate chain: sha256/... Pinned certificates for api.example.com (SSL / TLS)Certificate pinning f…Timeout d…

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