That is because of the UniFi controller which is a software used to manage all UniFi devices from a single webinterface. Even if this means you need to run some kind of server additionally (and I did not get it working on Linux on the first try because of a bug) the software defined networking stack makes the network management very easy unlike Cisco or Netgear.
The devices themself are running on Linux and allow you to connect via SSH if you need to get deeper into it. This might be the case if the IP of the controller changes. Than you use this to tell it the new controller IP: