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I understand from your post that your iPad shows it needs to be activated but you are receiving an error saying that it cannot find the server. First, make sure you have a good internet connection. The following article is mainly used if you iPad cannot connect to Wi-Fi, but the same steps can also be used to help refresh your Wi-Fi internet connection:
If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network - Apple Support
If you have a good internet connection, the steps from the following article while mainly used for iPhone activation issues, can also be used to resolve iPad activation issues:
If you can't activate your iPhone - Apple Support
Let us know how it goes.