support.steampowered.com/kb_article.php?ref=9121-WIFJ-7222Known Causes
* Most common: Bad or outdated router firmware (client-side)
* Less common: Bad or outdated router firmware (server-side)
If your connection to most servers fails with one of the error messages listed above (or you experience the other symptoms), this is a firmware issue with your router.
If your connection to one server fails, it is likely a problem with the network the server you are trying to connect to is operating on.
Troubleshooting
If you have a stand-alone router, bypass your router and plug directly into your modem to see if the connection continues to fail.
Please visit your router manufacturer's website for Firmware updates. If you have questions about installing or updating your Firmware, please contact the router manufacturer for assistance.
ActionTec DSL Modems which encounter this problem will need to be replaced, as no firmware update is available.
Recommended steps:
1. Disable QoS and uPnP. You need to go into the router and disable UPnP and QoS if it's there, and you should only have TCP/IP checked in the network properties for your Internet connection.
2. Disable Wireless Zero Service (included in Windows XP). You can access these settings in Control Panel > Administrative Tools > Services.
Routers with Known Issues
Actiontec DSL Modems
* Internal PCI Home DSL Modem (Model # PCI0839-01 )
* External USB Home DSL Modem (Model # UD800TP)
* USB/Ethernet Home DSL Modem (Model # ED800T)
* USB/Ethernet Home DSL Modem (With Routing Capabilities) (Model # R4500U)
Actiontec ADSL Gateways
* Wireless-Ready DSL Gateway (Model # R1520SU)
* Wireless-Ready DSL Gateway (Model # R1524SU)
* Wireless-Ready DSL Gateway (Model # R1520SU)
Actiontec Broadband Routers: Cable/DSL Routers
* 54 Mbps Wireless Cable/DSL Router (Model # GT704-WR)
* Wireless Cable/DSL Router (Model # R3010SUW)
* Wireless Cable/DSL Router (Model # R3010UW)
* Wireless-Ready Cable/DSL Router (Model # R1020S(U))
* Wireless-Ready Cable/DSL Router (Model # R1020S)
* Dual Mode Wireless-Ready Cable/DSL Router (Model # R3020QU)
Others
* Creative Labs BroadXent 8120 modem (5.0.0.16 17 November 2003)
* Netgear CG814WG
Routers with Known Firmware Issues
Linksys BEFSR11 and BEFSR41 V2, Linksys BEFSR81 ver.3
* Please visit Linksys for the latest firmware update available.