Hello there, Glider95.
It sounds like iCloud contacts aren't syncing to your iPhone 6s, even though they are between your MacBook Air and other devices. The following Knowledge Base article offers up some great, in-depth steps for troubleshooting:
Get help using iCloud Contacts
- Check the System Status page to see if there are known issues affecting iCloud Contacts, since your device might not be the cause of your issue.
- Make sure your date and time settings on your device are correct. You can easily fix issues caused by incorrect date and time settings by entering the right information.
- Make sure that you don’t lose important information by making copies of your Contacts.
- If you see duplicate contacts, you can remove them.
After each step, check to see if the issue still exists.
- Try to go to www.apple.com in Safari. If you can't connect to the Internet, your iCloud contacts won't update in the Contacts app. Get help with your Internet connection.
- Try to open a secure website from your iOS device to see if you can access ports 80 and 443. If the website doesn't open, you don't have access. Contact your Internet service provider for help. Safari requires access to port 443 to push updates between iCloud and your devices.
- Open Contacts and tap Groups in the upper-left corner.
- Pull down on the list to refresh the list of groups.
Check whether your device is set up to show iCloud contacts:
- Open Contacts and tap Groups in the upper-left corner.
- Make sure All iCloud is selected.
If you store and edit your contacts using your iCloud account instead of a third-party account, like Google or Yahoo, iCloud will automatically update your contacts. Check whether your contact is stored with iCloud:
- Open Contacts and tap Groups in the upper-left corner.
- Deselect the All [account] option for any third-party account, like Gmail or Yahoo.
- Make sure All iCloud is selected.
- Tap Done to see your list of Contacts. If you don't see the contact you're looking for, it's stored in another account.
- You can import the contact from a third-party service into iCloud.
If your device uses multiple accounts like iCloud, Gmail, and Yahoo, make sure that iCloud is your default Contacts account:
- Tap Settings > Mail, Contacts, Calendars.
- In the Contacts section, tap Default Account.
- Make sure iCloud is selected.
Close and restart the Contacts app on your iOS device.
- Double-click the Home button to see your open apps.
- Find the Contacts preview screen and swipe it up to close the app.
- Press the Home button to return to your Home screen.
- Wait a minute, then reopen the Contacts app.
- Tap Settings > iCloud.
- Turn off Contacts.
- You can choose Delete from My [device] if your data exists on icloud.com/contacts and one or more of your devices. Otherwise, choose Keep on My [device].
- Wait a few minutes, then turn Contacts back on.
Hold down the Sleep/Wake button, then drag the slider when asked to power off. Turn your device back on.
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Kind Regards.