Each Deco M4 unit is exactly identical. To set up the mesh system, a Deco M4 must be connected to the modem. This Deco unit becomes the master. The other Deco units are then simply added to the system and the mesh network is expanded accordingly. A configuration on the modem is not necessary. It is important to know that if the Mesh WLAN Deco System is used, then every device connected to it or connected under one of the Deco Mesh Routers will receive a DHCP address, i.e. if there are still LAN connections on the modem and devices are connected there, these devices will not be able to communicate with the Deco Mesh IP Address Range. The Deco Mesh Router system provides its own DHCP address range. If it is necessary for all devices to see each other, all devices connected to the modem must be connected to Deco Ethernet ports. Since each Deco device has 2 LAN ports, you can also connect a Gigabit Ethernet switch to a Deco device and then connect the LAN devices previously connected to the modem to the switch. This would ensure that all devices can see each other again.