jakman85andClaude Opus 5
874c6703f0
I took Plex down for the whole LAN. ADVERTISE_IP was http://plex-vip.${BASE_DOMAIN}:32400 -- a name that exists ONLY in PiHole's split-horizon answers and in no public zone. A Plex client resolves the advertised host ITSELF, with whatever resolver it uses, and on a real LAN that is frequently not PiHole: browsers ship DoH on by default, phones have "private DNS", guest/IoT devices take the router's DNS. Those clients could not resolve the name, the router answered the failed lookup with ITSELF, and they all landed on its web UI -- hence the %D certificate. Measured 2026-10-05: 192.168.2.1:443 -> C=ZZ, O=%D342e7e6b, CN=%D (router, LAN side) 136.51.115.252:443 -> the same %D cert (router, WAN side) pihole-0 AND pihole-1 -> plex -> .20, plex-vip -> .24 (both CORRECT) gateway .20:443 -> CN=*.home.keithjackson.dev, valid http://192.168.2.24:32400/identity -> 200 Plex's published connections: all port 32400, nothing on 443 The DNS was right; the DEPENDENCY on it was the bug. And since nothing Plex advertises listens on 443, the clients had left the Plex path entirely. Fix: <dashed-ip>.<serverhash>.plex.direct, which is RESOLVER-INDEPENDENT -- a public zone returning the private address embedded in the label, so every resolver (PiHole, the router, 1.1.1.1, a DoH browser) answers it with 192.168.2.24. No split-horizon entry, no Cloudflare record and no certificate work needed: the wildcard cert Plex already serves on 32400 covers that name. Re-verified today with full validation (no curl -k): 200, TLS verified. The nicer hostname cannot be made correct for clients that bypass PiHole -- a public record resolves to the WAN address and there is no NAT hairpin, so it is right only for PiHole users and wrong for the rest. There is no configuration of it that is right for both. PiHole's plex-vip answer is KEPT; it is just not what Plex advertises. Cost restated, not buried: the value embeds the VIP and the cert hash as a literal and nothing checks they still agree. Accepted because an unresolvable name is a worse failure -- silent, LAN-wide, and it points users at the router. UNVERIFIED: unreconciled, and the client-side resolver path is INFERRED -- my public-resolver probe was broken (NXDOMAIN even for a name that resolves) so I discarded it. The chain is the only explanation consistent with the measurements, but the NXDOMAIN-hijack step was not observed directly. Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>