You can use it as a wifi router with a DSL modem from Sunrise or as an access point. I would recommend using the access point mode and disabling the wifi from your DSL modem so there is no interference. The signal is really good and strong through several walls. I have 2 walls in between and a distance of about 12 metres. I still get a good 650 MBit with a 1GB line. I can really recommend the product.

Wifi but no DSL modem

In this case, it creates a second wifi network with a different name and you have to connect to it. No problem with Sunrise