The DHCP server of the Soihtu network shares the public, static IP address to each registered device, and the dynamic, non-public IP address to the devices waiting for registration. On the same occasion, the devices also receive the other network settings, such as the settings of the gateway and the name service.

As there is a limited number of public IP addresses accessible, only one device can be registered per apartment (two in one-bedroom and bigger apartments). If there are multiple devices with which one should get online in the apartment, the apartment requires its own routing equipment which offers its own corresponding DHCP service inside the apartment: the devices in the apartment receive a non-public address from the router, with which the device operates to the router, and the router brings the operation forward with a public address it has received at registration.

The DHCP server is a server the function of which is to share IP- addresses and other relevant network settings to the machines connected to the network. The IP addresses provided by the DHCP server can be either statically defined or they could be dynamically shared. A static IP address means that the machine always receives the same IP address. In the dynamic system, on the other hand, free addresses are given to the machines in the order in which they are connected to the network, and as the validity of the address expires, it is freed to the use of other machines.

You can gain more information about the DHCP technique on Wikipedia, for example: https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol