iPad says that it couldn’t reach the activation server

You should check this article: If you can't activate your iPhone - Apple Support. https://support.apple.com/en-us/HT201407

If your iPad is a cellular model, some have reported that temporarily removing the sim allows activation to complete.

Otherwise, 5 possible causes for that error message:

1] Activation server is actually down. Very rare occurrence, and of short duration when it

does happen. Solution - try again.

2] Your firewall and/or antivirus software are preventing the necessary connection. Solution -

temporarily disable your firewall and/or antivirus software until the activation completes.

3] computer being used for activation has been used to jailbreak an iOS device in the past.

Solution - use a different computer.

4] iPad has been jailbroken. Your favorite search engine may provide some direction, but jailbreaks often prevent

activations/updates from succeeding. Per Terms of Use for this forum, discussion of jailbroken iPads is

prohibited.

5] your region and/or timezone settings are inconsistent with your actual location. Solution - set region and/or timezone correctly.

There are multiple potential causes of this problem. If “waiting until later” has failed to provide satisfactory results, something other than availability of the Activation Server may be the cause. Here are some potential resolutions...

As an alternative to direct activation from the iPad itself, you might try activation by connecting the iPad to your PC (with iTunes installed) or a Mac (with iTunes or Finder).

It is possible that your WiFi router is unexpectedly blocking access to some internet/server resources - which might be resolved by a restart of your router.

To restart you home router, disconnect power - then wait at least 30 seconds before restarting. When you router has rebooted (which may take several minutes), force-restart your iPad:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On an iPad with Face ID: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

It is also possible that your currently selected DNS servers(s) are not resolving, or a blocking, some resource addresses. Changing your DNS Server IP Addresses might resolve this problem.

For recommended DNS servers (configured at your home router and/or your iPad), if only as a diagnostic tool, you might choose one of the following Recursive DNS Providers (IPv4 and IPv6 addresses included below). Where your local network is dual-stack, you should enter both the IPv4 and IPv6 redundant server addresses.

Quad9

9.9.9.9

149.112.112.112

2620:fe::fe

2620:fe::9

OpenDNS

208.67.222.222

208.67.220.220

2620:0:ccc::2

2620:0:ccd::2

Cloudflare+APNIC

1.1.1.1

1.0.0.1

2606:4700:4700::1111

2606:4700:4700::1001

If restart of your home router - or changing your DNS Server settings do not resolve the issue, you should directly contact Apple Support for assistance

Should it be necessary to escalate your issue to Apple Support, the quickest route to engaging with Apple Support will be via the Contact Support link at top-right of this page. Alternatively, you can initiate a support case using the Apple Support App:

https://apps.apple.com/gb/app/apple-support/id1130498044