Here are some troubleshooting steps you can follow to try to identify and resolve the issue with IIS:

  1. Check that the IIS service is running: Open the Services console (services.msc) and make sure that the World Wide Web Publishing Service is started.
  2. Check that the firewall is not blocking the traffic: Make sure that the Windows Firewall is configured to allow HTTP and HTTPS traffic to reach the server. You can check the Windows Firewall settings by opening the Windows Defender Firewall with Advanced Security console.
  3. Verify that IIS is listening on the correct ports: Use the netstat command to verify that the IIS service is listening on the correct ports (80 for HTTP and 443 for HTTPS). To do this, open a Command Prompt window and type “netstat -ano | findstr :80” to check for port 80 or “netstat -ano | findstr :443” to check for port 443.
  4. Check that the site bindings are correctly configured: Open the IIS Manager console and verify that the site bindings are correctly configured. Make sure that the site is bound to the correct IP address and port number.
  5. Check the website’s logs: The website’s logs (located in %SystemDrive%\inetpub\logs\LogFiles) may provide useful information on what’s happening with your requests. Check the logs to see if any errors are reported.
  6. Restart IIS: Sometimes, simply restarting the IIS service can resolve the issue. You can do this from the Services console or by typing “iisreset” into a Command Prompt window.
  7. Verify that DNS is resolving correctly: Make sure that DNS is correctly resolving the website’s domain name to the correct IP address. You can use the nslookup command to check DNS resolution.
  8. Test connectivity from the client side: Use a web browser or a tool like telnet to test connectivity to the website from the client side. This can help identify if the issue is with the server or with the client’s network.
  9. Check the server’s disk space: Make sure that the server has enough disk space available to store the website’s files and logs. Insufficient disk space can cause unexpected errors or prevent the server from starting.
  10. Verify that the website’s application pool is running: Open the IIS Manager console and check that the website’s application pool is running. If it’s stopped, try starting it and see if that resolves the issue.
  11. Check that the website’s files are accessible: Verify that the website’s files are located in the correct directory and that the IIS service has the appropriate permissions to access them.
  12. Test the website locally on the server: Access the website locally on the server by opening a web browser and navigating to “http://localhost”. If the website is accessible locally, then the issue may be related to network configuration.
  13. Verify that SSL is configured correctly: If you’re using HTTPS, verify that the SSL certificate is correctly installed and configured. You can use the SSL Checker tool to verify SSL configuration.
  14. Check the website’s error pages: Check the website’s custom error pages to see if any error messages are being displayed. These can provide useful information on what’s going wrong.
  15. Test with a different web browser: Try accessing the website with a different web browser to see if the issue is specific to a particular browser or client.
  16. Check for any pending Windows updates: Make sure that the server has all the latest Windows updates installed. Sometimes, issues with IIS can be resolved by installing updates.
  17. Verify that the server’s clock is set correctly: Check that the server’s clock is set to the correct time and time zone. If the clock is incorrect, SSL certificates may fail to validate.
  18. Use a network traffic monitoring tool: Use a network traffic monitoring tool like Wireshark to capture and analyze network traffic to and from the server. This can help identify any network issues that may be causing the problem.