Cause: After you grant Alibaba Cloud CDN permissions to access a private bucket, signature information is included by default for non-anonymous access when you retrieve an object from OSS by using CDN. However, to access the default homepage configured by using static website hosting, the request must be anonymous.
Solution: Configure a URL rewrite rule in the Alibaba Cloud CDN console. Set Path to Be Rewritten to ^/$, Target Path to /index.html, and Flag to Redirect.
After the configuration is complete, when a client requests www.example.com/, an Alibaba Cloud CDN point of presence (POP) returns the HTTP 302 status code to the client to re-request www.example.com/index.html.
For more information about how to configure URL rewrite rules, see Create an access URL rewrite rule.