The short answer
It depends on what kind of AI you have. Cloud-only AI -- ChatGPT, Gemini, Alexa, Google Home -- is gone the instant your WAN drops. Local AI on a small box in your closet keeps doing its job. We design for both modes and we document the failure behavior of each one before we install it.
What dies when the WAN dies
- Amazon Alexa: mostly dead. Local Echo features handle a small subset of commands offline (some lights, some routines), but the experience degrades sharply.
- Google Home: similar. A handful of local commands work, most do not.
- Apple HomePod with Apple Intelligence: better. On-device Apple Intelligence runs without network for many tasks. HomeKit local control survives WAN outages cleanly when the hub is on the LAN.
- ChatGPT, Gemini, Claude, Perplexity: all dead. They are cloud services.
- Crestron Home: the processor is local. Scenes, programmed logic, and direct control all survive. Only cloud-tied features (remote app access from outside the house, certain integrations) fail.
- Lutron RadioRA 3 / HomeWorks: local. Survives.
- Local AI stack (Whisper + Llama + Home Assistant): survives. Voice commands work. Scenes work. Camera analytics work. The only thing that does not work is reaching information that lives on the public internet.
Crestron Home autonomous mode
This is where the deterministic-control argument earns its keep. A Crestron processor running a documented logic stack does not need a cloud round trip to know what to do when you flip a switch, press a button, or trigger a sensor. Programmed scenes, schedules, climate logic, and security responses run on the processor. We design AI as a layer on top of this, not under it. When the WAN drops, the AI layer may degrade; the deterministic layer continues. Lights still work, climate still works, doors still work.
Home Assistant + local LLM continuity
For clients who want the AI layer itself to survive outages, we deploy Home Assistant on a hardwired box with a local LLM. Voice commands continue to be transcribed, parsed, and dispatched. The model cannot reach Wikipedia or Perplexity, so factual questions ("how tall is the Empire State Building") fail or fall back to a small cached knowledge base. Practical home commands ("dim the dining room," "play jazz on the patio," "turn on the heat in the guest house") all continue to work.
Cellular failover -- what it does and does not cover
A Ubiquiti UniFi or comparable router with cellular backup keeps the network up when the primary WAN drops. That keeps cloud AI alive in degraded mode (rate-limited, sometimes slow). It does not, by itself, give you AI resilience. It just gives you internet resilience. For a luxury home, we recommend cellular failover plus a local AI stack. Belt and suspenders.
FIELD NOTE
The clearest test is the hurricane test. Pull every WAN cable. Cellular failover unplugged. Walk through the house and confirm every "smart" feature you actually rely on still works. If voice control fails, scenes fail, lights stop responding to motion, your house was not built for resilience. We design for the test.
What we recommend for clients
For luxury homes in our service area, the default Restrepo design pattern is:
- Ubiquiti UniFi network with cellular failover at the gateway.
- Crestron Home processor as the deterministic source of truth for all home logic.
- Lutron RA3 or HomeWorks for lighting, locally bound.
- Local AI compute (Mac Mini or Mac Studio) running Whisper + Home Assistant Assist + a local Llama for voice and intent.
- Optional cloud reach-out for non-sensitive research and concierge tasks.
This stack passes the hurricane test cleanly. Voice and home control survive WAN outages. Cellular failover keeps non-critical cloud features alive in degraded mode. The client never has to choose between resilience and capability.
The hurricane test we run
On every install, we conduct a documented WAN-down test before sign-off. With the WAN physically disconnected at the demarc, we walk through:
- Voice control: does "dim the kitchen" still work?
- Scenes: does the "good night" scene still execute on schedule?
- Cameras: does Frigate still record and run analytics locally?
- Climate: does the thermostat still hold setpoint?
- Security: does the alarm still arm and disarm?
The client gets a written report. If anything fails the test, we either fix it or document the limitation. We will not sign off on a system that fails silently in an outage.