Here are a variety of resources helping with connectivity issues:
First try simply restarting your equipment and/or sign out and back in again, and try again. When using a Mac computer you can also try safe mode —> https://support.apple.com/guide/mac-help/start-up-your-mac-in-safe-mode-mh21245/12.0/mac/12.0
Choose your macOS version at the top.
If you can't connect to one of Apple’s services read this support article --> https://support.apple.com/108093 It offers multiple troubleshooting steps:
1. Check if there’s an server outage at Apple’s end for a service in your country or region. —> https://www.apple.com/support/systemstatus/
2. Make sure that your device is connected to the internet.
If you have multiple devices check if this is only an issue with this device, or is an issue with all devices. If you have a cellular device see if you can connect using that. Now read the support article for possible solutions depending upon the extent and nature of the connectivity problem.
3. Is your device software up to date?
If not, the article has links for ways to update different kinds of hardware.
4. Apple also suggests that you make sure the date and time are set correctly. Refer to https://support.apple.com/101619
Here's a related article about what to do if you can't connect or sign in to iCloud --> https://support.apple.com/HT203512
If your iPhone or iPad won’t connect to a Wi-Fi network, or if you have related connectivity issues, read this support article --> https://support.apple.com/HT204051
On a cellular device try resetting only network settings (be careful what you reset here!):
https://support.apple.com/guide/iphone/reset-iphone-settings-iphea1c2fe48/ios
If you use a VPN read this article —> https://support.apple.com/102281
You can try just turning it off but you may need to remove the VPN entirely.
If none of the resources provide a solution, contact Apple for assistance:
For support, click here --> https://support.apple.com/choose-country-region Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.
or:
Contact Apple for support and service --> "See a list of Apple phone numbers around the world."
Click here --> https://support.apple.com/HT201232