It’s possible that you have a DNS issue - such that your currently selected DNS servers(s) are not resolving, or are 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), you might choose one of the following Recursive DNS Providers (IPv4 and IPv6 addresses included below) - if only as a diagnostic tool. 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