Complete procedures with a way back.

Add a reviewed global IPv6 address alongside existing IPv4, learn the default route through authenticated network ownership rather than assumption, preserve Neighbor Discovery and Path MTU Discovery, and apply one consistent nftables policy to both families with timed recovery.

Deploy Blackbox Exporter 0.28.0 across independent external vantages with SSRF-safe egress, separate IPv4/IPv6 TLS modules, Prometheus relabeling, expiry alerts and nonpaging failure tests.

Diagnose Certbot AuthorizationError and failed ACME challenges without retrying blindly. Separate public DNS, IPv6, HTTP-01 routing, redirects, CAA, DNSSEC, DNS-01 propagation, and multi-origin failures before issuing or renewing a certificate.