When working with Nginx reverse proxy configurations, a common requirement is routing different subdomains to various backend servers with different IP addresses and ports. Here's a typical setup:

• Main domain: domain.com (IP: y.y.y.y, Port: 80)
• Subdomains needing proxy:
  • admin.domain.com → x.x.x.x:3434
  • user.domain.com → x.x.x.x:3435
  • vendor.domain.com → x.x.x.x:3436

Here's the core configuration you'll need in your nginx.conf or a separate config file under /etc/nginx/sites-available/:

server {
    listen 80;
    server_name admin.domain.com;
    
    location / {
        proxy_pass http://x.x.x.x:3434;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

server {
    listen 80;
    server_name user.domain.com;
    
    location / {
        proxy_pass http://x.x.x.x:3435;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

server {
    listen 80;
    server_name vendor.domain.com;
    
    location / {
        proxy_pass http://x.x.x.x:3436;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

For production environments, consider these additional parameters:

server {
    # ... previous configuration ...

    location / {
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_read_timeout 3600s;
        
        # Buffer and timeout settings
        proxy_buffering on;
        proxy_buffer_size 16k;
        proxy_buffers 4 32k;
        proxy_connect_timeout 600;
        proxy_send_timeout 600;
        proxy_read_timeout 600;
    }
}

For secure connections, add SSL configuration:

server {
    listen 443 ssl;
    server_name admin.domain.com;
    
    ssl_certificate /path/to/cert.pem;
    ssl_certificate_key /path/to/key.pem;
    
    location / {
        proxy_pass http://x.x.x.x:3434;
        # ... other proxy settings ...
    }
}

After making changes, always:

1. Test configuration: sudo nginx -t
2. Reload Nginx: sudo systemctl reload nginx
3. Check logs: tail -f /var/log/nginx/error.log

Common issues to check:

• DNS records for subdomains pointing to correct IP
• Firewall rules allowing traffic to backend ports
• Backend services listening on expected ports

For high-traffic scenarios, consider:

proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=my_cache:10m inactive=60m;

server {
    # ... previous configuration ...
    
    location / {
        proxy_cache my_cache;
        proxy_cache_valid 200 302 10m;
        proxy_cache_valid 404 1m;
        proxy_cache_use_stale error timeout updating;
    }
}

When setting up Nginx as a reverse proxy, a common requirement is routing different subdomains to distinct backend services. Here's the typical configuration pattern:

server {
    listen 80;
    server_name admin.domain.com;
    location / {
        proxy_pass http://x.x.x.x:3434;
    }
}


For your specific case with three subdomains, here's the complete configuration:

# /etc/nginx/sites-available/domain.com
# Admin Dashboard Service
server {
    listen 80;
    server_name admin.domain.com;
    
    location / {
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_pass http://x.x.x.x:3434;
    }
}

# User Portal Service
server {
    listen 80;
    server_name user.domain.com;
    
    location / {
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_pass http://x.x.x.x:3435;
    }
}

# Vendor API Service
server {
    listen 80;
    server_name vendor.domain.com;
    
    location / {
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_pass http://x.x.x.x:3436;
    }
}


Don't forget these critical proxy headers that maintain original request information:

Host: Preserves the original hostname
X-Real-IP: Passes client's real IP
X-Forwarded-For: Tracks request path



After configuration:
sudo nginx -t   # Test configuration
sudo systemctl reload nginx   # Apply changes


For HTTPS support, add SSL configuration:
server {
    listen 443 ssl;
    server_name admin.domain.com;
    ssl_certificate /path/to/cert.pem;
    ssl_certificate_key /path/to/key.pem;
    
    location / {
        proxy_pass http://x.x.x.x:3434;
    }
}



DNS records not properly configured for subdomains
Firewall blocking traffic between servers
Missing proxy headers causing backend issues