Swisscom WLAN box should help you here, but unfortunately with the internet box 2 (IB2) you do not have the advantage of the mesh network.
Either you upgrade to IB3 and add a new mesh-enabled WLAN box, or better yet, buy some wifi mesh system and disable the IB2 wifi.
In my 2nd home (not Swisscom) I have installed the Eero mesh system and I surf the web with nearly the same speed as next to the modem and have a ping of less than 10ms
Saluti e grazie
Alessandro
Abbonamento: inOne home + TV + mobile, pacchetto Sports.