Domain not working without "WWW"

Have you added www.domain.com to the list of Alternate domains in CloudFront? Your DNS record for www.domain.com should be a CNAME pointing to the Cloudfront DNS name (dxxxxxxxxx.cloudfront.net)

You can use a wildcard eg. *.domain.com as the alternate domain name, but you must make sure that the SSL certificate configured in your CloudFront distribution is also valid for *.domain.com - see documentation here: https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/CNAMEs.html#alternate-domain-names-wildcard

Could you show your HostedZone configuration?

You can check 3 places

• Route 53 HostedZone
• CloudTrail Alias
• Certificate Manager

and verify if there is everything ok and proper domains/subdomains are configured.

1. Please check if you have added your "www" domain in the list of Alternate domains in CloudFront configuration as Paul mentioned.
2. And make sure the ACM SSL certificate you have configured in CloudFront should be valid for both www and root domain. If not create a new one with both domains and reconfigure the CloudFront.