The "Cannot connect to server" message means your iPad lacks Internet access. You may be in an area without Wi-Fi signal, your Wi-Fi may be turned off or you may not have a network enabled. If you use a Wi-Fi + 3G iPad, this message means both your cellular data and Wi-Fi connections are not receiving service. A specific app or website may also be having trouble.
Troubleshooting
If your iPad tells you it cannot connect to the server when using Safari or any other iPad Internet browser, try loading a Web page on a different site. If the second site loads correctly,. the problem is the server used by the first site. This is a problem the site managers must deal with; all you can do is try visiting the site later. If no Internet sites will load, try launching the "Maps" or "Mail" app. If you can get new mail messages or search for directions, the problem is your browser app. In this case, close the app from the multitasking bar, then restart your iPad. If the problem is limited to your e-mail, contact your e-mail service provider for help solving the issue, which may require altering settings in your e-mail account through the "Settings" app. If no Internet-based apps work, the problem is your Internet connection.
Internet service
Check the upper left corner of your iPad. If you are connected to a Wi-Fi network, the wireless symbol of a cone of arcing lines will appear. The number of lines represents your signal level. If only the dot at the bottom tip of the cone appears, you may not have a strong enough signal for the iPad to detect, which will result in the "Cannot connect to server" message. If no symbol appears, you have no Wi-Fi connection. Cellular data signal will be noted in this area also, represented by bars, much like a cell phone. If neither signal type appears or you have minimal bars showing, your signal is too weak for an Internet connection.
Settings
Tap the "Settings" app on your iPad to access your Internet connection settings. If the "Airplane mode" setting is on, tap it to turn it off. This should restore any wireless settings you had before you placed it in "Airplane mode." For Wi-Fi settings, if the iPad says "Not connected" next to "Wi-Fi," tap the area that says that and choose a network from the list. Follow the onscreen instructions to enter the network password, if necessary. If no networks appear in the list, none are available in your area and you will not be able to connect your iPad until you are in an area with a wireless Internet connection. For Wi-Fi + 3G iPads, tap "Cellular data" to set up your cellular account with your iPad's carrier if you have not done this already. AT&T and Verizon iPads are each set up to let you connect with a specific carrier through an account set-up interface directly on the iPad. The service may take a few minutes to activate, but once it is activated you will receive a message. Tap the "Cellular Data" switch to "On" to enable an active connection.
Other issues
If you know you are connected to an Internet network and you still receive this error message, try rebooting your iPad. Outdated software can also be a source of glitches, so if rebooting does not work, try connecting your iPad to iTunes to sync it and update the operating system. The basic information screen for your device on iTunes will tell you if you have any software updates once you are connected.