10 Common Network Errors and How to Fix Them

What it means: The domain name doesn't exist in DNS. "NXDOMAIN" literally means "Non-Existent Domain."

Common causes:

• Typo in the URL (googel.com instead of google.com)
• The domain has expired or been deleted
• DNS records haven't propagated yet after a change
• Your DNS server is having issues

How to fix:

1. Double-check the URL for typos
2. Try the website in a different browser or device
3. Flush your DNS cache: Windows ipconfig /flushdns, macOS sudo dscacheutil -flushcache
4. Try a different DNS server (switch to 1.1.1.1 or 8.8.8.8)
5. Use LookMyIP's DNS Lookup to check if the domain has valid DNS records
6. If it's your own domain, check the DNS propagation status at lookmyip.com/propagation

What it means: Your browser reached the server, but the server actively refused the connection. The server is online but not accepting connections on the requested port.

Common causes:

• The web server (Apache, Nginx, etc.) is stopped or crashed
• The server is running on a different port than expected
• A firewall on the server is blocking the connection
• The server's IP has changed but DNS hasn't updated

How to fix:

1. Check if the site is down for everyone or just you (try from a different network or device)
2. Clear your browser cache and cookies for the site
3. If it's your server: check that the web server process is running, check firewall rules, verify the server is listening on the correct port
4. Use LookMyIP's Port Checker to verify port 80/443 is open on the server

What it means: Your browser sent a request but the server didn't respond within the timeout period. Unlike ERR_CONNECTION_REFUSED (server actively rejecting), a timeout means no response at all.

Common causes:

• The server is down or overloaded
• A firewall is silently dropping packets
• Network congestion between you and the server
• Your ISP is having routing issues

How to fix:

1. Wait a minute and try again — the server may be temporarily overloaded
2. Check your own internet connection (can you reach other sites?)
3. Try from a different network (mobile data vs Wi-Fi)
4. Run a traceroute to identify where the connection breaks
5. Check the server's IP using LookMyIP — has the IP changed? Is the server reachable?

What it means: Your browser and the server couldn't agree on an SSL/TLS protocol version or cipher suite for the encrypted connection.

Common causes:

• The server's SSL certificate is misconfigured
• The server only supports outdated TLS versions (TLS 1.0/1.1) that modern browsers reject
• The server's SSL certificate has expired
• Browser or antivirus software is interfering with SSL

How to fix:

1. Check the site's SSL certificate using LookMyIP's SSL Checker (lookmyip.com/ssl)
2. Try disabling your antivirus's HTTPS scanning feature temporarily
3. Clear your browser's SSL state (Chrome: Settings > Privacy > Security > Manage certificates)
4. If it's your server: update your TLS configuration to support TLS 1.2 and 1.3, renew expired certificates, and ensure the full certificate chain is installed

What it means: Similar to NXDOMAIN — DNS couldn't resolve the domain name to an IP address.

Common causes:

• DNS server is unreachable or malfunctioning
• Local DNS cache is corrupted
• Your network connection has DNS issues
• The domain genuinely doesn't exist

How to fix:

1. Check if other websites work — if nothing loads, your DNS server may be down
2. Switch to a public DNS server (1.1.1.1 or 8.8.8.8)
3. Flush your DNS cache
4. Restart your router
5. Check the domain with LookMyIP's DNS Lookup — if it resolves there, the issue is on your end

What they mean: These are server-side errors. A reverse proxy or load balancer (Nginx, Cloudflare, AWS ALB) couldn't get a valid response from the upstream server.

• 502 Bad Gateway: The proxy received an invalid response from the upstream server
• 503 Service Unavailable: The server is temporarily overloaded or down for maintenance
• 504 Gateway Timeout: The upstream server didn't respond within the time limit

Common causes:

• The application server behind the proxy has crashed
• High traffic is overwhelming the server
• The server is undergoing maintenance
• A deployment or configuration change went wrong

How to fix (as a visitor):

1. Wait and retry — these are usually temporary
2. Check the site's status page or social media for announcements
3. Clear your browser cache (sometimes stale cached pages show these errors)

How to fix (as the server operator):

1. Check that all application processes are running
2. Review server logs for crashes or resource exhaustion
3. Check if you've hit resource limits (CPU, memory, connections)
4. Verify database connectivity — a downed database causes cascading 502/503 errors

What it means: The website is stuck in a redirect loop — page A redirects to page B, which redirects back to page A, endlessly.

Common causes:

• Misconfigured HTTP-to-HTTPS redirect (each version redirects to the other)
• Conflicting redirect rules in the web server, application, and CDN
• WordPress site URL and home URL misconfigured
• Cloudflare SSL mode set to "Flexible" when the origin server also forces HTTPS

How to fix:

1. Clear your cookies for the site (redirect loops often involve cookie-based redirects)
2. Try in an incognito/private window
3. If it's your site: check for conflicting redirects in your web server config, .htaccess, application code, and CDN settings. Use curl -v -L to trace the redirect chain manually.

What they mean:

• 401 Unauthorized: The server requires authentication. You need to log in or provide valid credentials.
• 403 Forbidden: You're authenticated (or not required to be), but you don't have permission to access this resource.

Common causes:

• Directory listing is disabled and no index file exists
• File permissions are too restrictive on the server
• IP-based access restrictions are blocking you
• Your IP is flagged by a WAF (Web Application Firewall)
• Geographic restrictions or VPN blocking

How to fix:

1. Check if you need to log in
2. If you're being blocked, try from a different IP or disable your VPN
3. Check your IP's reputation using LookMyIP's IP Reputation Checker — you may be on a shared IP with a bad reputation
4. If it's your server: check file permissions (should be 644 for files, 755 for directories), verify .htaccess rules, and check WAF logs