Don't forget to download the latest firmware from the Zyxel website and flash it offline before you want to use it.
I forget, will you be using it in modem mode or modem/router mode? To set it to modem mode, what we conventionally call bridged mode, ask here for the settings! Perhaps also best done offline before connecting it. The Zyxel manual describes the setup for bridged mode as router-only

.
Using it in modem/router mode will screw up IPv6. Using it in modem mode feeding a router will be fine - depending of course on the router.
My broadband basic info/help site -
www.robertos.me.uk. Domains, site and mail hosting -
Tsohost.
Connection - Three 4G, tbb tests 35-45Mpbs down, 9-15 up.
==================================================
If you never think of anything off the wall, you'll never think of anything original.