For Type select LDAP Enter the IP address of your Domain Controller. In the Search scope, you have to enter the Base DN, you can find it by using ADSI Edit. Now for Authentication containers, click on Select button and choose the ones in which users that will have access through VPN are.

Virtual Private Network (VPN) Use a virtual private network (VPN) to integrate your instance with external data sources over the Internet. When configuring an integration that uses an encrypted protocol, such as Lightweight Directory Access Protocol (LDAP) or HTTPS, it is good practice to use the Internet as a transport mechanism. [SOLVED] FortiGate SSL VPN with LDAP problem - Networking May 20, 2020

To configure LDAP users for SSL VPN access, you must add the LDAP user groups to the SSLVPN Services user group. To configure SSL VPN access for LDAP users, perform the following steps: 1 Navigate to the Users > Settings page. 2 From the User authentication method drop-down menu, select either LDAP or LDAP + Local Users. The options change

May 20, 2020 Authenticating SSL VPN users using LDAP – lakkireddymadhu

If for example you have a group in your LDAP directory that is called VPN Users and you want only users from that group to be able to log on you can use the additional LDAP requirement option under Authentication, LDAP, in the Admin UI of the Access Server. Be sure that you specify the full DN or the query may fail to find the user in your LDAP directory.

OpenVPN LDAP for Windows Server download | Jun 09, 2014