Description of Zigbee
Zigbee is a standardised wireless low power communication protocol over short distances using "Bluetooth". It has a group of vendors, The Zigbee Alliance, cooperating for better compatability between product lines. Nedis is at the present NOT a member of this group. But Tuya is, as Nedis main supplier of OEM-products including the Smart Life app.
The benefit of Zigbee is low power on battery, usually lasting a year or so, the drawback short transmitting distances 10 meters or so and low data bandwidth max 250kbits/s, no good for cameras thus.
The security of transmissions aren made using 128-bit symmetrical keys, with known fixed fallback keys, thus the transmission is vulnerable.
There are three types of hardware:
The coordinator, which is the most capable of these. In Nedis product line it is the Zigbee Gateway, linking between Zigbee products and Wifi, usually used to attach to the Internet via a Wifi-router.
The router, which is both an application device (such as a switch, lamp, sensor..) and a mesh-router, capable of connecting other application devices with each other, routing their data, even if they are to far away from the coordinator for direct contact. Nedis does not offer any routers at the moment. But other Zigbee vendors routers might be used, when extended range beyond in line sight is required.
The end device. just an application device. It can not communicate with other devices just the coordinator directly or via the router. Nedis offers 5 such devices at the moment, but other Zigbee vendors products might be integrated to Nedis Gateway, just as other Gateways and Routers might be used with Nedis end devices. Check if vendors of other devices specs so that they comply to Zigbee ver 3.0 to be reasonably sure that they will work together with Nedis product line, even if there is no guarantee sadly.
I am NOT very fond of Zigbee as compared with Wifi for a couple of reasons. The starting cost of a Zigbee net as it requires a gateway of about 25-30€ and that does not include any application hardware (lamp, sensor etc.) The low security. The low transmitting distances. The low bandwidth. The no guarantee that Zigbee products from different vendors works together.
I have been using a few battery operated Tuya Wifi connected temperature and humidity sensors, connected via the Nedis Smart Life app and they have been working for a Year now on the same AA cheap batteries.