Intermittent access failures to odonto.ar from Claro Argentina

Hello Vercel team,

I'm experiencing intermittent access problems with my proyecjt odonto.ar, hosted on Vercel under the Hobby plan.

The website suddenly becomes unreachable and then starts working again without any changes on my side.

What I've observed:

The problem occurs on both Claro WiFi and Claro mobile data in Argentina.
It has happened repeatedly, on different days.
The application itself appears to be working: I can access it through the Vercel deployment's Visit URL.
My other Vercel project, https://portfolio-fdr-react.vercel.app/, works normally.

portfolio-fdr-react.vercel.app

Federico del Rincon

This makes me suspect a problem involving custom domain resolution, DNS, routing, or deployment configuration, something between vercel dns and/or Claro Argentina.

I also found a similar community report involving intermittent access from Claro Argentina: https://community.vercel.com/t/timeout-to-216-198-79-1-64-29-17-1-restores-custom-domain-access/51634

Could you please help me identify the cause and recommend the correct configuration for my domain?

I would particularly appreciate guidance on whether this could be related to Vercel DNS, edge routing, or connectivity from Claro Argentina.

I have not changed DNS records because I don't want to break the existing configuration.

Thank you.

Fixed! The problem is network reachability between Claro Argentina and part of Vercel's IP range. I tested from Claro (home and mobile) during an outage:

216.198.79.1 and 216.198.79.65 → connection timeout (ports 443 and 80)
64.29.17.1 and 76.76.21.21 → OK (200)

My domain uses Vercel DNS, which was returning only the 216.198.79.x addresses, so Claro users couldn't reach the site at all.

Workaround: I added manual A records in Vercel DNS (@ and www → 76.76.21.21). Vercel serves those instead of the automatic ones, and once DNS caches expired (~30 min), the site worked again for Claro users without them doing anything.

Could the Vercel team check the routing of 216.198.79.0/24 with Claro Argentina? Thanks!