The Easiest HA Firewall Setup I've Ever Done: UniFi Shadow Mode in 2026 [YouTube Release]

Additional Resources:

UniFi docs
https://help.ui.com/hc/en-us/articles/19581768432535-Shadow-Mode-High-Availability-on-UniFi-Cloud-Gateways

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Chapters
00:00 - Intro
00:34 - Requirements (Which Gateways Support Shadow Mode)
01:18 - Setting It Up in the UI
01:45 - Sync Status and Day-to-Day Management
02:01 - Firmware Updates with Zero Downtime
03:51 - Network Topology Options (MC LAG, WAN Switches, 5G)
04:28 - The Simple Single-WAN Setup
05:24 - How Failover Actually Works (MAC + ARP + State Table)
06:21 - The DAC Cable Quirk You’ll See
07:14 - What If the Primary Dies for Good? (Promoting the Shadow)
08:17 - Dual WAN with Two ISPs
08:49 - 5G Backup as Failover (GRE Tunnel)
09:39 - The UniFi Protect Caveat
10:10 - Outro