Question about Zyxel Multy X Mesh System - set of 2

The Multy X Mesh System does not replace the Sunrise modem. 1 Zyxel device is plugged into the LAN connection of the modem. On the mobile phone you then have to load the Multi X App and open an account with Zyxel. After logging into the Multi X App with your account, it is possible to add both devices. The devices then automatically synchronise with each other.

is not a replacement for a modem of a provider. is simply a wifi router. can therefore replace (or supplement) the functionality wifi of the modem.
idea is: one of the devices is connected to the LAN via patch cable, then configured via app (only possible via app). this takes a little time, you have to be patient with the part.
then connect the second device to the power supply (without patch cable!). then configure it again with the app or have it configured. the devices should be arranged "sufficiently" far apart (read the instructions on the box).
the devices communicate with each other with their own separate connection (independent of the wifi connection, which is then used by the clients), so they do not eat any hay away from it.