Articles & Guides
Useful resources for web developers and system administrators
Monitoring
Website Slow to Load: Causes and Fix
Website slow to load? Break it down by phase: DNS, TCP, TTFB, render. Use curl to measure each phase, then a list of causes and fixes to speed your site up.
Monitoring
Website Not Loading: Why It Happens and a 10-Step Fix Checklist
Website not loading? Read the browser error, find the failing layer (device, DNS, TLS or server) and fix it with exact commands for visitors and site owners.
Monitoring
Cloudflare Error 1020 Access Denied Fix
Cloudflare Error 1020 Access Denied means a WAF or Firewall Rule blocked the request. How to find the triggered rule, read the logs, and remove the block.
SSL/TLS
Cloudflare 525 SSL Handshake Failed Fix
Cloudflare error 525 SSL Handshake Failed means the TLS handshake with the origin failed. Check the origin certificate, use openssl s_client, and fix SSL modes.
HTTP
Cloudflare 522 Connection Timed Out Fix
Cloudflare error 522 Connection Timed Out means your origin server did not answer in time. Diagnose the origin, check the firewall, use curl, and fix it.
DNS
DNS_PROBE_FINISHED_NXDOMAIN: Fix It in Chrome, Mac and Android
DNS_PROBE_FINISHED_NXDOMAIN means the name did not resolve. Fix it in Chrome, Edge, Mac and Android: cache flush, secure DNS, dig checks and owner-side fixes.
Networking
ERR_CONNECTION_RESET Fix
ERR_CONNECTION_RESET means the connection was dropped midway. Learn the causes of a TCP reset, diagnose with curl and traceroute, and fix it step by step.
SSL/TLS
ERR_SSL_PROTOCOL_ERROR Fix
ERR_SSL_PROTOCOL_ERROR is a failed SSL/TLS handshake. Learn the causes, diagnose with openssl and curl, and fix the certificate and protocol step by step.
DNS
ERR_NAME_NOT_RESOLVED Fix
ERR_NAME_NOT_RESOLVED means the browser couldn't turn the domain into an IP. Learn the DNS causes, diagnose with nslookup and dig, and fix it step by step.
Networking
This Site Can't Be Reached: Fix by Error Code (Chrome, Android)
Fix "This site can't be reached" by its ERR code: a code table, down-for-everyone test, DNS flush, one-site and Android fixes, sudden blocks and server checks.