Featured AI Products
Compute
Build, deploy, and scale cloud compute resources
Containers and Images
Safely store and manage containers and backups
Managed Databases
Fully managed resources running popular database engines
Management and Dev Tools
Control infrastructure and gather insights
Networking
Secure and control traffic to apps
Security
Help protect your account and resources with these security features
Storage
Store and access any amount of data reliably in the cloud
Browse all products
AI/ML
CMS
Data and IoT
Developer Tools
Gaming and Media
Hosting
Security and Networking
Startups and SMBs
Web and App Platforms
See all solutions
Community
Documentation
Developer Tools
Get Involved
Utilities and Help
Become a Partner
Marketplace
Pricing

- Community
- DigitalOcean
- Community
- DigitalOcean

Cloudfare Host is down error 521

Posted on March 7, 2021

i added ip4 of cloudfare into iptables but still when i go to my website using https i get Error 521 : Web server is down. Please help its urgent

This textbox defaults to using Markdown to format your answer.

You can type !ref in this text area to quickly search our full set of tutorials, documentation & marketplace offerings and insert the link!

These answers are provided by our Community. If you find them useful, show some love by clicking the heart. If you run into issues leave a comment, or add your own answer to help others.

alexdo

March 8, 2021

Accepted Answer

Hello there,

Error 521 occurs when the origin web server refuses connections from Cloudflare. Security solutions at your origin may block legitimate connections from certain Cloudflare IP addresses.

You can also make sure that port 443 is open with this command:

iptables -A INPUT -p tcp -m tcp --dport 443 -j ACCEPT

Also, you can check our tutorial for whitelisting IPs with iptables:

https://www.digitalocean.com/community/tutorials/iptables-essentials-common-firewall-rules-and-commands#service-web-server

Regards, Alex

The developer cloud

Scale up as you grow — whether you're running one virtual machine or ten thousand.

View all products

Start building today

From GPU-powered inference and Kubernetes to managed databases and storage, get everything you need to build, scale, and deploy intelligent applications.