nslookup challenges.cloudflare.com If it returns NXDOMAIN or a timeout, your DNS is blocking it. If it returns a valid IP (like 104.16.xxx.xxx ), the issue is higher up (browser or IP reputation). | Problem Source | Best Fix | |---------------------------|-----------------------------------------------| | Browser extensions | Disable ad-blockers / privacy tools | | VPN / proxy IP flagged | Turn off VPN or switch server | | DNS failure | Change to 1.1.1.1 or 8.8.8.8 | | Antivirus blocking | Allowlist the domain | | Corrupt hosts file | Remove any line pointing to that domain | | ISP or network-wide block | Use mobile hotspot or VPN (ironically) |

Once you complete the challenge successfully, you should be unblocked for that website for a period of time (usually hours to days).