Some folks have discovered that changing their DNS service fixes FaceTime connection issues. The ideal way is to configure your modem/router with DNS service, but often settings in Settings/Wi-Fi on your iPad will override the router settings.
Try either of these;
Google Public DNS
220.127.116.11, 18.104.22.168'09 Mac mini, '06 iMac, iPad 2, Mac OS X (10.6.8), iOS (4.3.3) Mac fanboy since 1984!