Nginx subdomains not working

2 min read 07-10-2024

Nginx Subdomains Not Working: Troubleshooting & Solutions

Setting up subdomains with Nginx can sometimes be a frustrating experience, especially when they refuse to work as expected. This article will guide you through common issues and solutions when encountering subdomain problems in your Nginx configuration.

The Scenario:

Imagine you've set up a website with the domain example.com and are trying to add a subdomain, say blog.example.com, to host a blog. You've configured Nginx, but when you access blog.example.com in your browser, it either leads to a blank page, an error message, or redirects you to the main domain.

Here's a basic Nginx configuration for blog.example.com that could be causing problems:

server {
    listen 80;
    server_name blog.example.com;

    root /var/www/blog;
    index index.html index.php;

    location / {
        try_files $uri $uri/ =404;
    }
}

Common Causes & Solutions:

DNS Configuration: The foundation of subdomain functionality lies in your DNS records.
- Incorrect A Record: Ensure you've created an A record for blog.example.com that points to the server's IP address where Nginx is running.
- CNAME Record: While A records are often used for subdomains, using a CNAME record (especially for subdomains like www.example.com) can sometimes cause issues with Nginx. Make sure you're using the appropriate record type for your setup.
- DNS Propagation: After updating your DNS records, it can take some time for the changes to propagate globally. Patience is key here, but you can use tools like WhatsMyDNS to check propagation status.
Nginx Configuration: Your Nginx configuration needs to explicitly define the subdomain's server block.
- Server Name: Double-check that the server_name directive in your server block matches the subdomain (blog.example.com) exactly.
- Root Directory: Ensure the root directive points to the correct directory on your server where the content for the subdomain is located.
- Virtual Host Conflicts: If you have multiple server blocks in your Nginx configuration, make sure the server_name directives don't conflict. Avoid using wildcard entries like *.example.com unless you're very careful about potential security implications.
Firewall Rules: Firewalls can sometimes interfere with access to subdomains.
- Port 80 (HTTP): Ensure port 80 is open on your firewall to allow HTTP traffic to reach your server.
- Port 443 (HTTPS): If you're using HTTPS, make sure port 443 is also open.
Web Server Restart: After making changes to your Nginx configuration, it's crucial to restart the web server to ensure the new configuration is loaded.
- Linux/macOS: Use the command sudo systemctl restart nginx or sudo service nginx restart depending on your system and configuration.

Additional Tips:

Use a tool like curl or wget to test the connection to your subdomain directly from the server, bypassing any browser-related issues.
Check your server logs (e.g., /var/log/nginx/error.log) for error messages related to the subdomain.
Consider using a virtual host management tool like Certbot or Virtualmin for simplified subdomain configuration and management.

By systematically examining these points and working through the suggested solutions, you'll be well on your way to resolving the subdomain problems in your Nginx setup and ensuring that your website functions as intended.

Nginx subdomains not working