Dual-stack means your server answers correctly on both IPv4 and IPv6 for the same hostname. LogicWeb VPS plans include two IPv4 addresses on the smallest plan, and IPv6 is on by default. Addresses in the panel are only the start; DNS, listeners, firewall rules, and certificates must all work on each stack you publish.
Using the two IPv4 addresses
The two IPv4 addresses sit on the guest as separate addresses, not as two websites and not as a routed block. You choose how virtual hosts and services bind to them. A clean split is one address for the website and one for mail, or one in production and one held as a spare. The second address is easy to overlook until an allow-list only names the first IP and mail leaves from the other. IPv6 is a third path, so count every address when you write allow-lists. Reverse DNS is set per address. If both IPv4 addresses will ever send mail, each one needs a PTR record that matches the HELO name you use.
DNS for dual-stack
An A record is a promise that something answers on that IPv4 address. An AAAA record is the same promise for IPv6. Publishing AAAA only because it felt modern, then watching AutoSSL HTTP-01 follow the broken IPv6 path, is a common failure. Clients still prefer IPv6 when a AAAA record exists. Publish AAAA only when you mean it, or leave it out. A leftover AAAA at an old host after you moved the A record can keep serving traffic on mobile networks long after the cutover.
Sockets, TLS, and how to test
A process listening on 0.0.0.0:443 is not listening on ::. Some stacks bind both families; others do not. If a AAAA record exists, the virtual host and the certificate must answer on IPv6 as well. AutoSSL and HTTP-01 will follow AAAA when it is published. A firewall that only allows IPv4 can make issuance fail in a way that looks like Let’s Encrypt is down.
dig example.com AAAA +short
curl -6 -sI https://example.com | headThe first command shows the DNS promise. The second shows whether anything kept it. If dig returns a AAAA and curl -6 hangs or returns a different certificate, you do not have dual-stack yet; you only have a DNS record. Repeat the check with curl -4 and compare the results. Keep firewall rules aligned for IPv4 and IPv6 together. Two IPv4 addresses plus a working AAAA is a solid default. Two IPv4 addresses plus a decorative AAAA is an outage you will meet first on a phone.
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