ERR_CONNECTION_TIMED_OUT on some websites, network-wide.

Troubleshooting Network-Wide ERR_CONNECTION_TIMED_OUT Errors: A Guide to Diagnosing and Resolving Connectivity Issues

Experiencing connectivity problems can be frustrating, especially when they affect certain websites while others remain accessible. Recently, many users have reported encountering the “ERR_CONNECTION_TIMED_OUT” error on popular browsers like Google Chrome, alongside similar timeout messages on Android devices using Firefox. This article explores a common scenario and provides actionable insights to diagnose and resolve such network-wide issues.

The Scenario: Unreachable Websites Despite Successful Pings

Imagine noticing that key services like speedtest.net, Discord, and other popular sites are inaccessible, displaying timeout errors. Interestingly, when pinging these sites’ domains, responses come back without errors, indicating that the IP addresses are reachable at a basic level. However, performing traceroute (tracert) reveals that packets are getting lost or stuck at certain points in the network path.

In such cases:

Pings to problematic sites succeed, suggesting DNS resolution might be functional.
Traceroute results point to potential routing issues or blocks at intermediary network nodes.
Essential services like YouTube, Gmail, and Google work flawlessly, indicating that the problem isn’t with internet connectivity in general but specific to certain domains or routes.

Common Causes and Diagnostic Steps

DNS Configuration:
Your DNS settings (e.g., 8.8.8.8 and 8.8.4.4, Google DNS) are correctly configured and typically reliable. Since DNS resolution isn’t failing, the issue likely lies elsewhere.
Routing Problems:
The traceroute outputs help identify where packets are getting delayed or blocked. If traceroutes to certain sites hang or show abnormal delays, this suggests routing issues, which could be caused by:
ISP routing misconfigurations
Network congestion
Firewall or filtering rules at some point in the network
Regional or global internet outages affecting specific routes
Firewall and Security Software:
Local firewalls or security settings may be blocking outgoing connections to specific domains or IP ranges.
ISP-Level Restrictions or Outages:
Sometimes, ISPs implement filtering or face outages affecting particular routes or services.