If you've been experiencing problems finding servers or being dropped randomly, try this fix from the Steam forums by user Epsilon. It's the ONLY thing that worked for me, and it straightened out EVERYTHING on my setup as far as connection problems. Enjoy!:

Okay, I found some advice online that says basically the following:

1.) Check your windows update history: Control Panel\System and Security\Windows Update

2.) On the left hand side, click "View update History"

3.) Scroll down to around March or February, or sort by name, and see if you find a "Ralink - WLAN - 802.11n USB Wireless LAN Card" update. It's an Optional update.

4.) If you don't see that update as Status: Successful, then... well... dang, I have no idea.

5.) If yes, and I'm guessing that your answer is "Sh**, I do see that..." then do the following:

5a.) Go to your device manager (If you can't get here, I feel sorry for you), expand your "Network adapters" and right-click on whatever your primary adapter is, (for me, it's Medialink MWN-USB150N), and click "Properties."

5b.) Go to the Driver tab.

5c.) Freaking click "Roll Back Driver" because the driver you have installed right now is F---ing. S--t. Up.

6.) Restart your computer.

............(7-13 is Steam specific)

14.) You're welcome, I hope.

Cheers,

Ian L
epsilonmm

Full link here: http://steamcommunity.com/discussions/forum/1/864961721799252661/