What are the network's recommandations Devialet are suggesting for a Phantom Setup – Devialet Help Center

Phantom is able to communicate with your home environnement by 3 differents ways:

PLC - Power Line Carrier (through your domestic electrical set up).
Ethernet
Wifi (the wifi signal from your internet router)

In a large house, we suggest to set a dedicated Wifi network for your Phantom, this is allow a full wifi bandwidth to your Phantom and extend your internet connection to your phantom place.

Most of the time we use an Apple Airport express for this because it's an easy routeur to configure, but you can find similar product in the market with the same capability.

The airport express can be configurated in two different way

as an extension of your existing wifi (the one in place with your internet router)
as a new wifi network

Both options are working with Phantom, you need to notice by the way that the extension option is dependant from your internet router, therefore if your domestic wifi have some signal drop, the extension will face the same issue.