Is a Zyxel AP compatible with other brands of wireless routers?

Zyxel_Judy

Although other brands of wireless routers cannot act as the Zyxel AP's controller, you can still deploy any Zyxel access point to extend your existing router's wireless coverage. Wireless clients will still be able to roam between your router and Zyxel access point.

Follow the step-by-step guide here:

How to configure the AP to extent my existing wireless network? — Zyxel Community