VLAN filtering rolled back - ZX1 needs physical reconfiguration

docs/06-CHANGELOG.md

@@ -1,5 +1,23 @@
 # Infrastructure Changelog
 
+## 2026-01-27
+
+### VLAN Filtering Rolled Back
+- [VLAN] Enabled VLAN filtering - caused connectivity issues
+- [VLAN] ZX1 switch unreachable after activation (no management IP responding)
+- [VLAN] CSS326 traffic routing through ZX1 (not direct eth3 link)
+- [VLAN] **Rolled back** - VLAN filtering disabled
+- [CONFIG] Added eth4 (ZX1) to all VLAN tagged lists for future use
+- [STATUS] Network back to Legacy mode (192.168.31.0/24)
+- [TODO] Need physical access to ZX1 to configure VLAN trunking
+
+### Issues Identified
+- ZX1 switch not responding on documented IP 192.168.31.22
+- ZX1 may need VLAN trunk configuration before re-enabling filtering
+- All CSS326 traffic goes via ZX1→HAP1, not direct CSS326→HAP1 link (STP?)
+
+# Infrastructure Changelog
+
 ## 2026-01-26
 
 ### VLAN Filtering Activated ✅