? Renew lease on iPad and iPhone

Last night my wife's iPad and iPhone somehow disconnected from the WiFi and I can't get them back on line. What I'm getting is a message to 'renew lease' and I've got no idea what this means or how I get past this block and reconnect to the WiFi router. In the meantime, my wife's getting more upset as she can't access her apps. Any suggestions?JohnRobinson