This is possible without any problems, because Deco units can be used completely independently of each other. Each set contains completely identical units that can also be used individually. You can even mix all Deco models with each other. For example, it is possible to use a Deco E4 with only 100 Mbit network connections as a low-cost WLAN mesh and connect an M4 with 1 Gbit Ethernet to the modem or router of the Internet provider, in order to benefit from a fast Gbit Internet, for example. If the Internet connection today only offers a maximum of 100Mbit, you can use the E4 system; later, a Deco Mesh can be expanded at any time.