Vercel custom IDN domain returns HTTP 200 but response body stalls during download

Ivanfalkov · 2026-03-31 15:34:15.691198

Hi everyone, I have a static site deployed on Vercel that works correctly on the project domain but hangs on my custom IDN domain. ## Affected Domains **Working domain:** **[https://greenhouse-eosin.vercel.app/](https://greenhouse-eosin.vercel.app/)** — full page loads normally **Affected domain:** **[https://www.xn–90ahalobcoje5a6c9c.xn–p1ai/](https://www.xn--90ahalobcoje5a6c9c.xn--p1ai/)** — browser shows infinite loading ## Issue Details * No redirect loop * Response starts with `HTTP 200 OK` * Body download stalls at ~21,085 bytes (out of 154,162 total) * Same deployment and content load fully on the `.vercel.app` domain ## What I've Tried 1. Re-added both domains (`www` and apex) in project settings 2. Set `www` as primary, apex as redirect 3. DNS is delegated to Vercel nameservers 4. Cleared local DNS and browser caches 5. Tested in multiple browsers 6. Verified with `curl` — custom domain stalls, `.vercel.app` completes ## My Guess Something in edge routing / CDN path / TLS handling specific to IDN domains. Has anyone experienced similar issues with IDN (punycode) domains? Any suggestions appreciated!

Hi mate! I tested both domains and couldn’t reproduce a global issue, both return 200 and load the full ~154 KB HTML with identical content, so this doesn’t look like a deployment or DNS problem.

Given your symptom (stalling around ~21 KB), this points to a region / edge / protocol-specific issue (likely a Vercel POP or HTTP/2/HTTP/3 behavior affecting the IDN hostname).

Things that would help confirm:

Force HTTP/1.1 vs HTTP/2 with curl
Test from another network (mobile/VPN)
Share a failing x-vercel-id

If it only happens in certain networks/regions, Vercel can trace it to a specific edge node.

I think your setup looks correct, this is very likely on the edge delivery side. hope this helps

Hi team hope this helps!

Behavior

200 OK returned
Response stalls at ~21 KB (expected ~154 KB)
No redirect loop
Reproducible by user (browser + curl)
.vercel.app works normally

Verification

When successful, both domains return identical content (same size, hash, headers)
Range requests work
DNS and deployment appear correct
Issue not globally reproducible

Interpretation

Likely edge-specific issue (region/POP/protocol), possibly: