Network connectivity troubleshooting

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Troubleshooting network connectivity issues
Please follow these steps to diagnose network connectivity issues within Steam:

Check the Steam server status.
Check the Steam server status page to ensure that the issue you are encountering is not related to system downtime. If you encounter timeout errors when trying to access Steam sites, there is most likely a general system issue, and Steam will not be accessible until that issue is resolved.
Test your router
The article Using a Router with Steam includes steps to isolate problems if they occur in the router.

Wireless and powerline connections can cause interference and generate intermittent failures. If possible, test Steam with a direct cable connection, to determine if this is the problem. An Internet speed test can also help you identify problems related to the quality of local links.
Troubleshooting firewalls
See the article Using a firewall with Steam for instructions on how to test and configure your firewall for Steam.

Note: If you are installing Steam for the first time or Steam has recently been updated, a firewall may be preventing Steam from connecting to the Steam network, even if Steam was working properly before the update was applied.
Disabling background applications
Review the article Programs that can interfere with Steam article and reconfigure, disable or uninstall any programs that may be preventing Steam and Valve games from connecting.
Viruses, Trojans, adware and spyware.
Scan your computer for Spyware, malware, adware or viruses that interfere with Steam.



Ports required for Steam
All ports required to run the Steam application are listed here. Some Steam games may require their own available ports.

Note:
Many networks and university proxies block the ports required by Steam. Please check with your network administrator to ensure that the required ports are open if you are connecting through a network or university proxy. Steam required ports cannot be redirected over HTTP or reconfigured to a custom port range.



Known issues with Internet Service Providers (ISPs).
Important:
If you notice that your Steam connection only has problems during certain times of the day (for example, in the evenings between 17:00 and 23:00), it is possible that your ISP is blocking or "bandwidth throttling" your connection. Please test your connection at other times of the day and contact your ISP directly if you think this is causing the connection problem.

Some internet providers seem to often block ports necessary for Steam and its games to function properly:
012.net (Steam traffic blocked).
Bluewin (Firewall blocks Steam from the provider side - must be disabled through the provider's service portal).
Dutch Telecom (Steam traffic blocked).
ISPFree (Steam traffic blocked).
Micronet Broadband (Steam traffic blocked).