What it means
Routers may label a network Guest while still allowing some local traffic, or may isolate clients so completely that a phone app cannot reach its smart plug. The security property is the traffic rule, not the name broadcast by the router.
A real-world example
A camera is moved to Guest Wi-Fi. It still reaches the owner's printer on the main network because the router's isolation option was left off.
What to do
Read the router's guest-network controls, enable the separation you need and test both device function and inability to reach unrelated main-network services.
The distinction that matters
A distinct password prevents casual joining but does not on its own create segmentation. Isolation reduces lateral access, not internet exposure through the gadget's cloud service. If a hub must bridge networks, document the exception instead of disabling every boundary. Test after firmware updates too, including router updates.
FTC connected-home networking
