Welcome to Android Central! Which phone? I assume they work fine on mobile data? Does this happen on any wi-fi network or just your own? If it's your own, try rebooting the router by unplugging its power for 30 seconds. If that doesn't work, try the tips here: http://forums.androidcentral.com/am...roubleshooting-wi-fi-connection-problems.html, especially the one about disabling IPv6.