VPN software to connect multiple Zyxel USG 20s to a cloud based IPsec VPN?

I currently have Zyxel USG20s all over the world connected to a Zywall 110 which is connected to a server running Squid web proxy. I’m trying to replace the server with AWS or any other cloud services and the Zywall 110 with a VPN software.

I’ve looked into AWS and I’m able to set up squid web proxy and run from that. However I’m not sure how I am able to replace the Zywall 110 with a VPN software. I’ve looked into using OpenVPN software but it does not support IPsec.

Are there any VPN software which would work well with AWS and work over IPsec?