Steam “Connect” Protocol

As the Steam errors are quite vague, and can refer to a lot of different things, there's not an exact solution. However, the best way to troubleshoot it, is by eliminating various causes.

1. The most common issues can be solved deleting the ClientRegistry.blob file and force Steam to download a new and fresh copy of it.

   The clientregistry.blob is a file for the program Steam. The file holds your registration data for your games. If you delete it the file will be restored and you will have all of your default settings on all games installed (like your name, spray, binds, etc)

   • Go to C:\Program Files\Steam (or the Steam directory that was specified during installation).
   • Locate ClientRegistry.blob and delete or rename the file to ClientRegistryOld.blob.
   • Next time you start Steam, the file will be forced to download.
     
     

2. Another common issue is the update list can become corrupt, this is solvable by deleting the AppUpdateStats.blob file and forcing Steam to download a new and fresh copy.

   • Go to C:\Program Files\Steam (or the Steam directory that was specified during installation).
   • Locate AppUpdateStats.blob and delete or rename the file to AppUpdateStatsOld.blob.
   • Next time you start Steam, the file will be forced to download.
     
     

3. If none of the above work, you should try to start Steam on another computer on the same network, to check for router problems.

   • If Steam doesn't start on another computer on the same network, it indicates that there is a problem with the router.
     • Your router might need port forwarding. Portforward.com is a great site for tutorials on how to forward ports on a lot of routers.
   • If Steam starts on another computer on the same network. It's something with your computer that's causing issue.
     
     

4. If you have a firewall, try disabling it and start Steam.

   • If Steam starts your firewall might be blocking it. If you are using Windows Firewall, navigate to Control Panel\All Control Panel Items\Windows Firewall\ and press the "Advanced Settings" button on the left side. Then press the "Restore Default Policy" as this image shows.
     If you are using another firewall, please consult the firewalls manual to figure out how to restore the default settings.
     
     

5. Some programs may interfere with Steam and it's connectivity.

   • Check your latest installed programs with Steam's list for programs that might interfere.
     
     

6. Some Spyware, Adware, and Viruses also interfere with Steam.

   • Scan your computer for viruses, spyware and adware with an Anti-Virus program of your chose. If would recommend the free version of AVG, if you are in need of a Anti-Virus program.

It looks like similar users share your frustration for this annoyingly horrible issue:

However, it seems there are several fixes for this that have worked for other users:

Solution A:

Rolo: for me, this problem was caused by a optional windows update, ralink wlan 802.11n usb wireless lan card. I fixed it by going to device manager, network adapters, driver, roll back drivers. hope this helps someone.

Solution B (similar to A, for Win7):

Seismoid: I had the same problem with my steam client ("Could not connect to steam network", then after deleting everything but steam.exe and /steamapps folder "steam client has to be online to update", then after uninstalling steam and trying to reinstall it took ~20 tries until it downloaded the 110mb without error, but still kept getting errors that it could not connect to steam network). In my case I just took a look at the windows update history (win7) and found out that the wlan driver was updated on march 5th. So I rolled back that update and everything worked again. You might want to give it a try if you have similar issues with your steam client as those mentioned in this thread.

(I use Windows 7) First you should check if there is an update of your wireless driver in the update history.

1. Go to Control Panel -> System and Security -> Windows Update
2. On the left side click "View update history"
3. Look for a line that says "Ralink - WLAN - ..." (in my case it was "Ralink - WLAN - D-Link DWA-140 RAngeBooster N USB Adapter", my wlan stick); hint: you just have to check the last 2-3 weeks - or whenever your steam client stopped working - so sort the updates by a click on "Date Installed" at the top ;)
4. If there was an update and you want to try to roll back:
5. go to Control Panel -> System and Security -> System
6. click on "Device Manager" on the left side
7. expand the "Network adapters" node in the device tree
8. right-click on your wireless adapter mentioned earlier (here it only says "D-Link DWA-140 ..." - no "Ralink - WLAN -" as prefix)
9. choose "Properties" in the context menu
10. go to the "Driver" tab and click "Roll Back Driver"
11. wait until windows is done rolling back (you may need to restart; though I didn't have to)
12. dont install those drivers again if steam client works now :) (might need to deactivate automatic windows updates)

It seems in most of the cases, Steam's problem stems from a bad Wi-fi or network driver. It also doesn't hurt to check your antivirus or any firewalls running. See if disabling all anti-virus software while running Steam should work. Some users have found that their AVs were in fact blocking Steam.