Lightsail Distribution produces an error

I just enabled distribution for my website, but getting an error:
What is wrong?

klionsky-org
SSL certificate, klionsky.org
Requested on:July 3, 2021, 1:15 AM
Status:Valid, in use

Distribution:
Status: Enabled
Default domain: d19p3ng5aeb0ha.cloudfront.net
Custom domain: klionsky.org

504 ERROR
The request could not be satisfied.
CloudFront attempted to establish a connection with the origin, but either the attempt failed or the origin closed the connection. We can't connect to the server for this app or website at this time. There might be too much traffic or a configuration error. Try again later, or contact the app or website owner.
If you provide content to customers through CloudFront, you can find steps to troubleshoot and help prevent this error by reviewing the CloudFront documentation.
Generated by cloudfront (CloudFront)
Request ID: 9B24Qe-WXe2ooIWsb0DPhIaBgYK2TRekbjFhNsHYAc0rZ6GuLECMwg==