When deploying IPv6, the currently most often deployment model is to dual-stack the end-user's LAN. Combined with the Happy Eyeballs (RFC 8305/6555), this often masks broken IPv6 deployments.
Still, there are tools that do not perform Happy Eyeballs -- and for those tools, a broken IPv6 networking configuration results de facto in a broken service, even in dual-stack environment where the IPv4 counterpart is available. In IPv6-only network, broken IPv6 connectivity and/or DNS configuration results in IPv6 hosts being completely inaccessible.
This talk will focus on real-life brokenness experience and how to avoid it.