Zyxel ZyWALL 350 with existing modem/router

I need to integrate a Zyxel ZyWALL 350 usg into an existing network with the main goal of having client to site VPNs.

since I can't see the firewall from the outside, I'm asking if I did it right:

- Actual modem/router/gateway is 192.168.1.1

- I connected the wan port on the Zyxel to a router port

- I set the zyxel wan to 192.168.1.10 with gateway to 192.168.1.1

- I forwarded the TCP/UDP ports 500,4500,443 from the router to 192.168.1.10

- PCs on LAN will be connected to the LAN2 port on 192.168.2.X

I followed the Zyxel guides to create both IPSec and SSL VPNs, but in no case the client sees the firewall, pointing to the router public IP. I tried the deployment of the configuration, but does not reach the server

Something conceptually wrong in the above configuration?