Would using an older wifi router that you have lying around as a anti-smart device network work? Fire it up with no WAN signal. It's just a radio broadcasting a

Would using an older wifi router that you have lying around as a anti-smart device network work? Fire it up with no WAN signal. It's just a radio broadcasting an SSID that you can connect a device to. Are the "smart" devices smart enough to know there is no WAN signal and keep searching for a different connection, or will it be tricked into not being able to connect to the internet?