System software updates can, in some circumstances, trigger a problem with the iPad (or iPhone) internal routing table. The causes are many, but are usually attributable to some types of App or associated device configuration.
If you have a VPN App or profiles installed, or a security App such as Norton, these may be interfering with your network routing to some internet server resources. The resolution is usually simple; if installed, you may only need to temporarily disable and/or remove the Security App and/or VPN. After removing the offending App, a restart of your WiFi Router and devices may be necessary.
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:
Force restart iPad (models with Face ID or with Touch ID in the top button)
If your iPad doesn’t have the Home button, do the following:
- Press and quickly release the volume button nearest to the top button.
- Press and quickly release the volume button farthest from the top button.
- Press and hold the top button.
- When the Apple logo appears, release the top button.
Force restart iPad (models with the Home button)
Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
After restarting, attempt to install the update.
If this resolves your issue, the VPN and/or security App can be reinstated after the connectivity problem has been resolved.