Update DNS to Quad9 DoH, add port utilization diagrams

- Both AdGuard instances now use Quad9 DoH (dns.quad9.net)
- Bootstrap DNS: 9.9.9.9, 149.112.112.112
- New 02-PORT-UTILIZATION.md with ASCII diagrams for all devices
- Fixed Tailscale container DNS and route configuration

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/06-CHANGELOG.md

@@ -28,3 +28,20 @@
 ## Previous Changes
 
 See git history for earlier changes.
+
+## 2026-01-25 (Update 2)
+
+### DNS Configuration
+- [DNS] Updated both AdGuard instances to use Quad9 DoH
+- [DNS] MikroTik AdGuard: upstream=https://dns.quad9.net/dns-query
+- [DNS] Unraid AdGuard: upstream=https://dns.quad9.net/dns-query  
+- [DNS] Bootstrap DNS: 9.9.9.9, 149.112.112.112
+
+### Containers
+- [CONTAINER] Fixed Tailscale container authentication
+- [CONTAINER] Tailscale DNS changed from 8.8.8.8 to 172.17.0.1,1.1.1.1 (fallback)
+- [CONTAINER] Tailscale route fixed: 100.64.0.0/10 → 172.17.0.3
+
+### Documentation
+- [DOCS] Created 02-PORT-UTILIZATION.md with ASCII port diagrams
+- [DOCS] Updated 09-MIKROTIK-ADGUARD-DOT-DOH.md with Quad9 DoH config