WebGUI show Site to Site VPN is up but traffic cannot pass through

Zyxel_Kevin

Checking:

1)You have allow ESP Protocol from WAN to Device. Firewall cannot decrypt packets without allowing ESP rule.

2)You have allow rule for zone "IPsec_VPN" if you use Policy based VPN

(If you customize the VPN zone, please make sure you have the corresponding allowed rules)

3)Check you have correct static route/policy route if you use Route based VPN.

4)Check there is no overlap addresses with the peer subnet

You go to Maintenance -> Packet Flow Explore -> Routing Status to check all routes.