mytps.app fails on Android (ERR_HTTP2_PING_FAILED), Vercel subdomain works

Help
1

Current behavior

I have a Next.js application deployed on Vercel.
Custom domain:

Vercel deployment:

The application loads correctly on:

  • macOS
  • iPhone (Safari)
  • Desktop Chrome
    However, on Android devices the custom domain never loads.
    Chrome reports:
net::ERR_HTTP2_PING_FAILED

The browser eventually shows a blank white page.
The important part is that the Vercel deployment URL works perfectly on the exact same Android device, browser and network.
Only the custom domain fails.

Expected behavior

Both domains should behave identically because they point to the same deployment.

What I tested

  • Multiple Android phones
  • Multiple Android browsers
  • Wi-Fi and mobile data
  • Different networks
  • DNS verified
  • SSL verified
  • Vercel domain configuration verified
    Results:
  • https://tps-app-theta.vercel.app :white_check_mark: Works
  • https://mytps.app :cross_mark: Fails only on Android
    curl returns:
HTTP/2 200

DNS resolves correctly.
Chrome DevTools consistently reports:

net::ERR_HTTP2_PING_FAILED

I also confirmed this is not an application bug because the exact same deployment works through the Vercel subdomain.

Project information

Framework: Next.js
Hosting: Vercel
Project: tps-app
Custom domain:

Deployment URL:

Could someone from the Edge Network team investigate whether there is a routing or HTTP/2 issue affecting the custom domain?
Additional observations:

  • The issue reproduces on multiple Android devices.
  • The issue reproduces across multiple Android browsers.
  • The same Android device, browser and network load https://tps-app-theta.vercel.app successfully.
  • Only https://mytps.app fails.
  • Chrome DevTools reports: net::ERR_HTTP2_PING_FAILED.
2

The domain troubleshooting guide can help with most custom domain configuration issues. You might be able to use that guide to solve it before a human is available to help you. Then you can come back here and share the answer for bonus points.

You can also use v0 to narrow down the possibilities.

3

Additional finding:

We discovered that enabling a VPN on the same Android device immediately resolves the issue.

Without a VPN:

With Turbo VPN enabled:

Additional information:

  • The issue reproduces on multiple Android devices.
  • It reproduces in multiple Android browsers.
  • The same Android device and network load https://tps-app-theta.vercel.app successfully without a VPN.
  • Only the custom domain fails.
  • This strongly suggests a routing or network path issue rather than an application issue.
4

Update:

After additional testing, the issue is not Android-specific.

The custom domain https://mytps.app is inaccessible from Russia without a VPN on:

  • Android
  • iPhone
  • macOS

The issue reproduces on both Wi-Fi and mobile data.

As soon as a VPN is enabled, the site loads immediately on all devices.

The Vercel deployment URL https://tps-app-theta.vercel.app remains accessible without a VPN.

This suggests the issue is related to routing or accessibility of the custom domain rather than the application itself.