Works over IPv6, with gaps: www doesn't fully work over IPv6; its mail servers lack IPv6; its nameservers lack IPv6.
Website over IPv6 duocnguyenmmo.store has an AAAA record and answers on it.
✓ 2001:df7:ce00:19::3:0 answers · 443
yes
www over IPv6 www.duocnguyenmmo.store has no AAAA record.
no
Mail servers (MX) have IPv6 None of the mail servers has an AAAA record.
gw.oxmail.vn ✗
no
Nameservers have IPv6 No nameserver has an AAAA record — an IPv6-only resolver can't reach this domain's DNS.
sapa.vclouddns.com ✗laocai.vclouddns.com ✗
no
HTTPS over IPv6· not part of the grade yet Redirects to www.duocnguyenmmo.store, which has no IPv6 address — so IPv6 visitors end up needing IPv4 after all.
https://duocnguyenmmo.store/ via 2001:df7:ce00:19::3:0→ 308https://www.duocnguyenmmo.store/ · redirects to www.duocnguyenmmo.store, which has no IPv6 address
problem
What's keeping duocnguyenmmo.store from an A
www.duocnguyenmmo.store is an alias of 900441b8863068a0.vercel-dns-017.com, which has no IPv6 www.duocnguyenmmo.store is a CNAME, so it can't also have its own AAAA record. Ask whoever runs 900441b8863068a0.vercel-dns-017.com to enable IPv6 there — or replace the alias with the A and AAAA records they give you. Why some hosts don't offer IPv6
A redirect leads off IPv6 Redirects to www.duocnguyenmmo.store, which has no IPv6 address — so IPv6 visitors end up needing IPv4 after all. Give the redirect target IPv6 too, or redirect somewhere that has it.
Mail servers without IPv6 gw.oxmail.vn has no AAAA record, so mail from IPv6-only servers can't reach it directly. If a provider runs your mail, that's their setting; if you run it, add AAAA records for these hosts.
Nameservers without IPv6 sapa.vclouddns.com, laocai.vclouddns.com all have no AAAA record, so a resolver that only speaks IPv6 can't look your domain up. Most DNS providers offer IPv6 nameservers; ask yours, or move DNS to one that does.