Summary:
We’re seeing SSL issues with our custom domain https://requests.thesqd.com on some Macs. The same project works fine when accessed via the default Vercel domain (*.vercel.app). We’d appreciate help tracking down what’s going wrong.
Current Behavior
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The custom domain fails to load in Safari and Chrome on multiple Macs (including macOS Sequoia 15.4.1 — fully up to date)
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curl on those Macs returns:
SSL certificate problem: self signed certificate in certificate chain
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The same site works:
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From other Macs (e.g., mine)
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When using the fallback prf4.vercel.app domain
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Also tested on multiple networks, including hotspots — issue persists
Expected Behavior
- Custom domain (requests.thesqd.com) should work consistently across all Macs and browsers, especially with a valid SSL chain
Debug Info
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SSL Labs test shows:
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Grade: A+
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Chain issues: None
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Trusted by Apple, Mozilla, Windows, Android
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DNS (GoDaddy) is properly configured:
- requests.thesqd.com → CNAME to cname.vercel-dns.com.
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No DNSSEC or caching issues
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No issues on our hosting project otherwise
Repro Steps
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Open https://requests.thesqd.com on a Mac (Sequoia 15.4.1)
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Use curl or Safari — SSL error appears
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Open same page on https://requests-squad.vercel.app — loads fine
** Project Details**
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Hosted on Vercel
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Custom domain: requests.thesqd.com
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Vercel fallback domain: prf4.vercel.app
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Using automatic HTTPS (Let’s Encrypt)
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Framework: Next.js (but issue appears before any client code runs)
Hypothesis
We think this may be due to Vercel edge nodes caching a partial certificate chain for our custom domain. We’ve seen a similar issue before with Fillout + custom domains using Let’s Encrypt’s R10 intermediate.
What we need help with:
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Can we force Vercel to fully reissue the SSL cert and flush edge caches for the custom domain?
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Is there a deeper issue with how Vercel serves the Let’s Encrypt R10 chain to Apple clients?