Why is my guest network not working?

Zyxel_Jami

If guest network clients cannot access the internet, ensure that both the DNS server’s MAC address and the gateway’s MAC address are added to the Layer 2 isolation whitelist.

You can configure this under Configure > Access points > SSID advanced settings. These MAC addresses must be entered correctly so the access point can forward DNS traffic; otherwise, clients may connect to the WiFi network but fail to resolve domains, resulting in no internet access.