Zyxel VMG3625-T50B, langaton reititin/DSL-modeemi/4-porttinen kytkin, valkoinen

I plugged this router in behind my livebox to extend my wifi network (several large stone walls, so unsuitable repeaters). The router is connected to the box via an rj45 cable from an ethernet port on the box to the wan input on the zyxel router. Both are in default configuration and the firmware is up to date. I'm having the following problem: if I access the internet via the zyxel router, only the google, youtube, instagram and wikipedia sites are accessible. The rest of the web is inaccessible. Has anyone ever had this problem? To solve this problem, change the IP address of the LAN IP SetUp: it is 192.168.1.1. 192.168.0.1 should be set (home networking > lan setup).