The search functionality only looks for games on your local network. Any game you wish to connect to that is not local will need an IP address entered manually. Please see the Port Forwarding post if you wish to host a game for your friends or the Online Connection Alternative post if you do not have the ability to do port forwarding.
Source: Steam Community (opens in a new tab)
Build and release context
Recorded Steam release date:
Within one calendar day of this post (UTC). The listed date does not establish an exact launch time.