iPad backup won’t complete

These are the somewhat basic and quite obvious, (IMO) suggestions from Apple copies form here.

If you can't back up to iCloud or restore from iCloud backup failed - Apple Support

If a message says that your last backup couldn't be completed

1. Check that you're connected to Wi-Fi.
2. Ensure your device is up to date.
3. Try to back up on another Wi-Fi network.
4. If you still need help, contact Apple Support.

It has been a while since this happened to me but what I always tried was this series of steps.

• Turn off iCloud backups, if possible. Restart the device, turn the backups on again and try a manual backup.
• If I get the spinning wheel when trying to turn off the backup, force close the settings app, restart the device, try a manual backup.
• Force restart my device and try another backup.

Heritageguy wrote:

Thanks for the reply. Tried your suggestions with no results. This started after we changed internet provider. Thinking maybe there’s something there. Thanks again for trying to help.

Realizing that your phone backs up fine and that everything else works internet related, it might be worth a try to reboot your router.