Raspbian to fortigate

Can anyone please help me setup a raspberry pi to create a tunnel between my office and the raspberry pi that is connected to a a mobile device for internet

However the raspberry pi network is not standard network configuration it uses the same NetworkManager as Ubuntu so that I could forward the wlan0 internet through to the eth0 as shown below:

https://raspberrypi.stack...=1#comment143993_89806

setup should look something like this:

   laptop   <lan>   Fortinet   <lan>   public ip   )))) internet ((((   public ip   <wifi>   raspberry pi   <lan>   ethernet device

192.168.x.x         196.x.x.x               Static                                Dynamic                 192.43.x.x                192.168.x.x

I do not know how to setup the /etc/ipsec.conf file

We are using PSK which I understand goes in to the /etc/ipsec.secrets file

Fortinet config I have is as follows:

Phase 1:

AES128-SHA256,AES256-SHA256,3DES-SHA256,AES128-SHA1,AES256-SHA1,3DES-SHA1

DH GROUP 14,5

Key Lifetime = 86400

XAUTH - disabled

Phase 2:

AES128-SHA256,AES256-SHA256,3DES-SHA256,AES128-SHA1,AES256-SHA1,3DES-SHA1

DH GROUP 14,5

Enabled replay detection >

Enabled PFS

Key Lifetime seconds

Seconds 43200

Yes I have seen many other sites out there but none of them I have managed to get working hence why I am begging for help on this please...