Here is the response from our department responsible:

Unfortunately, we cannot guarantee stability as many things can cause the wireless signal to be interrupted, such as interference from other products.
WPS is optional for connection. Wi-Fi Protected Setup (WPS) is a feature provided with many routers. It is designed to facilitate the process of connecting to a secure wireless network from a computer or other device.
Is the customer referring to connecting the TV to the stereo speakers? In this case, Grunding has a line input that he can connect to if his TV has a 3.5 mm output but not for headphones. If he has the mentioned port, he can use the following.

Cable: Cordial CFY WCC Connection Cable (3m, Mid-range, 3.5mm jack, RCA)
Alternatively, he would need this adapter to convert the Toslink output to RCA output: Delock Digital to HD analogue audio converter (Audio switch, Digital -> Analogue)

We can suggest an alternative that is available and has an RJ45 input to connect the internet router directly to the stereo via an ethernet cable like this one:
Stereo system: Panasonic SC-HC2040 (40W, Bluetooth, WiFi, CD Player, Spotify Connect, Chromecast integrated, Multiroom)

In this case, the customer would need the adapter from above and this cable: Bandridge 3.5mm stereo plug BLUE - RCA stereo (2m, Mid-range, 3.5mm jack, RCA)
And an ethernet cable like this one: Roline Network Cable (S/FTP, Cat. 5E, 300cm)