Hello Vercel Community,

I need help investigating a persistent issue with my custom domain: https://www.lumeraa.ru/

My website works perfectly on its Vercel deployment URL: https://lumera-website-phi.vercel.app/

However, the custom domain displays a blank screen because the main JavaScript file does not download completely.

Here are the test results:

1. The deployment URL downloads the JavaScript bundle successfully:

• HTTP 200 • 252,462 bytes downloaded • Approximately 0.45 seconds.

1. The custom domain fails to download the exact same file:

• HTTP 200 initially • Content-Length: 252,462 bytes • Download stops at approximately 20,706 bytes. • Connection eventually terminates. • Error: curl: (56) Failure when receiving data from the peer.

1. Browser console error: net::ERR_HTTP2_PING_FAILED
2. The problem occurs across multiple devices and networks:

• Desktop on home internet. • Desktop using a mobile hotspot. • iPhone Safari over LTE.

1. Cloudflare DNS proxying is disabled: Both lumeraa.ru and www.lumeraa.ru are set to DNS Only (grey cloud).
2. Vercel confirms that DNS records, SSL certificates, and domain routing are healthy. Both custom domains show Valid Configuration and are assigned to Production.

Affected request ID: arn1::7zvbl-1794260375023-a1d0a680d03a

The deployment itself appears healthy. The problem seems specific to delivering static assets through the custom domain.

Could someone from the Vercel team help investigate whether this might be related to Vercel Edge Network, HTTP/2, or custom-domain asset delivery?

Thank you!