Best practices
HTTP/2, compression, caching, consent, privacy links and the basics of a well-built site.
- Best practices9 min read
ERR_ADDRESS_UNREACHABLE: when there is no route to the address
ERR_ADDRESS_UNREACHABLE means your device found no route to the site's address. A VPN remnant, broken IPv6 or a stale router causes most cases.Updated 29 Oct 2026 - Best practices10 min read
Is my website down? The 5-minute triage
A website down checker tells you whether your site is down for everyone or just you. Here is the 5-minute triage, and what to do in the first 10 minutes.Updated 28 Oct 2026 - Best practices10 min read
ERR_CONNECTION_TIMED_OUT: what the silence means and how to fix it
ERR_CONNECTION_TIMED_OUT means the browser asked for a connection and nothing ever answered. Clear the visitor-side causes in minutes, then find what is swallowing packets on the way to your server.Updated 26 Oct 2026
Fix pages
Delivery and page weight
4 of 7- How to enable HTTP/2 and HTTP/3Medium impact.Fixes
http2-negotiated+32 min - How to enable Brotli or gzip compressionMedium impact.Fixes
brotli-or-gzip1 min - When a CDN helps and how to add oneFor information.Fixes
cdn-detected1 min - How to set cache headers for static filesMedium impact.Fixes
cache-headers1 min
HTML and JavaScript
4 of 6- Why HTML validation errors matterFor information.Fixes
html-valid-errors-count1 min - Doctype and the basics of a valid documentMedium impact.Fixes
doctype1 min - How to declare the character encodingMedium impact.Fixes
charset1 min - How to fix JavaScript console errorsMedium impact.Fixes
console-errors1 min
Privacy, cookies and consent
4 of 6- Trackers and cookies before consent: how to make the banner actually block themMedium impact.Fixes
cookies-before-consent+11 min - How long should cookies live?For information.Fixes
cookie-lifetime1 min - Cookie banners and consent: what to checkMedium impact.Fixes
cookie-banner-reject-button+11 min - How to run analytics with Google Consent ModeFor information.Fixes
consent-mode-detected1 min
Trust and site basics
3 of 3Check all 28 at once
The HTTP/2 & HTTP/3 test runs every check on this page against your site.