I am experiencing an ISP-specific connectivity problem with my production custom domain:
The domain consistently fails to load when accessed through MTN Nigeria 5G/mobile data, while the Vercel deployment URL works on the same MTN connection.
I have tested this on two different iPhones using MTN Nigeria, with the same result. The custom domain also loads immediately when I enable a VPN on the same device.
Tests already performed:
- Safari and Chrome both fail on MTN.
- Vercel.com loads normally on MTN.
- The Vercel deployment URL loads normally on MTN.
- mindmed.com.ng loads immediately when using a VPN.
- Two separate MTN iPhones show the same issue.
- There are no AAAA records.
- Cloudflare DNS is being used, but the DNS records were originally DNS-only.
Current DNS configuration:
- @ A → 76.76.21.21
- www CNAME → cname.vercel-dns.com
- No AAAA records
Following Vercel’s recommendation, I also tested enabling Cloudflare Proxy on both records. This did not restore access from MTN. Instead, the browser eventually reported that it could not establish a secure connection. I reverted the records to DNS-only.
This appears consistent with an ISP-specific network/edge routing or reachability problem rather than an application problem.
I am unable to run the Vercel Connect Debug Script because I only have an iPhone and the diagnostic currently supports macOS/Linux and Windows.
Could you please investigate the Vercel edge/network path serving mindmed.com.ng from MTN Nigeria and advise whether there is an affected Vercel edge IP/routing path or another supported workaround?
This is a live public-facing mental health service, so accessibility from Nigerian mobile networks is important.