What broke, how it was diagnosed, and the exact fix. Only things that really happened, with dates. Titles describe the symptom as seen at the time, not the conclusion. A postmortem is a full write-up; a note is a few paragraphs about a pitfall.
2026
- postmortem IPv6 works, DHCP renews fine, ARP answers, and not one IPv4 packet gets through RouterOSAT&T BGW