Roger Hayter wrote:
It would be entirely possible to have an isolated WiFi network, either
using VLANs or a separate access point. This might actually simplify
the control of some sensors.

Indeed it is. However the business model of a lot of wifi stuff is they're
controlled via a cloud app or backend. If you take the internet away, they
tend to break.

A sizeable chunk of the Chinese wifi smart home stuff is controlled via an
ESP8266 that can be reprogrammed with more sensible firmware, but it's nice
for things to be designed out of the box to be local only as they are with
Zigbee and Z-wave.

Theo