GoDoFi deployment fails on mobile data with ERR_CONNECTION_CLOSED

Hello Vercel Community,

I need help diagnosing a connectivity issue with my project.

Production: https://godofi.vercel.app Preview: https://godofi-b19jcthll-go-do-fi.vercel.app

Both URLs work on my home Wi-Fi and PC, but neither opens on my iPhone over 4G. Both Chrome and Safari fail; Chrome reports ERR_CONNECTION_CLOSED. The main website, https://vercel.com, does open over the same mobile connection.

I ran read-only diagnostics from my PC:

Both deployments are Ready.
Both URLs return HTTP 200 from the PC.
TLS certificate validation succeeds.
Tested Vercel IPv4 addresses return HTTP 200.
DNS answers vary by resolver, but both hostnames resolve to Vercel IPv4 addresses.

I have not changed any project settings, DNS records, code, or deployments during this investigation.

Could this be related to mobile carrier routing, DNS resolution, or connectivity to Vercel's edge network? What diagnostic information would help narrow down the cause?

Thank you.

Update: I tested both production and preview URLs on my iPhone. They fail on mobile data with ERR_CONNECTION_CLOSED, but the production URL opens successfully when I enable a VPN.

Both URLs work on my PC and home Wi-Fi. Could you help investigate a possible ISP routing, DNS, IP filtering, or Vercel Edge connectivity issue?

Production: https://godofi.vercel.app Preview: https://godofi-b19jcthll-go-do-fi.vercel.app