Intermittent 10–15 second stalls only on custom .ru domain while .vercel.app remains fast

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1

Hello.

I have a Vercel Hobby project called Capsule2007.

The deployment itself works perfectly:
https://capsule2007.vercel.app

However, the custom .ru domain:
https://www.capsule2007.ru

randomly stalls for 10–15 seconds.

Important observations:

  • .vercel.app domain is always fast;

  • custom .ru domain alternates between instant loads and 10–15 second hangs;

  • issue is reproducible many times per day;

  • DNS and SSL were verified;

  • Cloudflare proxy was disabled and re-enabled during testing;

  • Vercel agent already confirmed:

    • DNS is correct;

    • SSL is correct;

    • traffic reaches Vercel edge;

    • no deployment/runtime issues detected.

We also ran the Vercel debug script during the issue, and it failed with:
“Range lookup failed - No response from API”

This seems related to edge routing/network path instability specifically affecting the custom .ru domain.

Region:
Russia / Europe routing path.

Could someone from the infrastructure/network team check:

  • edge routing;

  • TLS negotiation path;

  • regional routing;

  • or possible instability affecting .ru custom domains?

Thank you.