Correct. I think they use Zwave as the radio link. Same with WEMO from Belkin.
The absolutely easiest way to control any of this stuff is to use Node-RED running on a Raspberry Pi. Drag and drop everything you need to control the Hue etc and then tie it all together with suitable HTTP or MQTT commands (MQTT server also runs on the Pi) and with this setup, everything is internal to your network.
MQTT is about the easiest way to get all your devices talking to each other.You can even use MQTT on an external server so you have access to your devices from anywhere. A secure connection is also supported so the system can be made secure.