DrayTek - Are you still searching for a VPN solution for your company? Don't want to change the existing network of the company? Why not using the "Single-Arm VPN" solution. It's quick,
Set up VPN with Two Factor Authentication(TOTP) on Smart VPN Client | DrayTek
How to setup Site-to-Site VPN between Unifi USG and Draytek Vigor | by Heang Yuthakarn | Medium