Why does hosting external resources on a subdomain not resolve the "Access-Control-Allow-Origin missing" error in Webflow? Is it because the Webflow site is not hosted on the same server as the subdomain and is only pointed to with an A record? Is there another solution or a way to set header policies in Webflow to address this issue?

Hosting external resources on a subdomain does not resolve the "Access-Control-Allow-Origin missing" error because Webflow does not provide server-level access to configure CORS (Cross-Origin Resource Sharing) headers. Even if your subdomain is pointed to Webflow via an A record, Webflow treats it as a separate origin, and there is no built-in way to modify response headers.

Why This Happens:

1. Webflow Does Not Allow Header Configuration
   Webflow's hosting does not allow direct modifications of HTTP response headers, including CORS policies.

2. Different Origins Despite Subdomains
   Browsers enforce the same-origin policy, meaning example.com and cdn.example.com are considered different origins unless CORS headers explicitly permit sharing.

3. DNS A Records Do Not Unify Origins
   Pointing a subdomain to Webflow via an A record does not create a true same-origin relationship. Headers must still be set at the server level.

Alternative Solutions:

• Host External Resources on a Server Where You Control Headers
  If possible, use a server (e.g., AWS S3, Cloudflare Workers, Firebase Hosting) where CORS headers can be configured.

• Use Webflow’s Asset Hosting
  Upload assets directly to Webflow’s CMS or static asset manager to avoid the cross-origin issue.

• Configure CORS via a Proxy Server
  If you control another server, set up a simple proxy that fetches the resources and adds the necessary CORS headers.

Summary:

Webflow does not allow direct CORS header configuration, even on subdomains. To resolve this, use a hosting provider where CORS can be configured or store assets directly in Webflow.