Here’s my setup at present:

Huawei E3372 (Public IP) to AR-150 (LAN IP 192.168.3.1) to Ubiquiti USG (LAN IP 192.168.1.1)

So I’m getting confused with the three devices and their respective IP address settings. Can anyone help with the correct settings so I can access the VPN on the USG from the WAN side?