With the VPN Server package, you can turn your Synology NAS into a VPN server so users can remotely and securely access resources shared within your local area network. Synology lists these supported VPN protocols: PPTP, OpenVPN and L2TP/IPSec.
For OpenVPN and L2TP/IPSec, the knowledge base says the setup is done in VPN Server and that the necessary files/credentials must be provided by the VPN server administrator. For OpenVPN-related client setup, the SRM knowledge base says to choose OpenVPN (via importing an .ovpn file) and then:
1. Click Browse to import the .ovpn file exported from the VPN server.
2. Enter the username, password, and import the CA certificate file.
3. If provided, import the TLS-auth key, client key, client certificate, or certificate revocation list in Advanced options.
4. Click Next.
5. Optionally enable:
- Use default gateway on remote network
- Allow other network devices to connect through this Synology server's Internet connection (Wireless AP only)
- Reconnect when the VPN connection is lost
6. Click Apply.
For L2TP/IPSec, the knowledge base says to:
1. Choose L2TP/IPSec and click Next.
2. Enter the address of the VPN server, your username and password, and the pre-shared key.
3. Click Next.
4. The username, password, address, and pre-shared key should be provided by the VPN server administrator.
A note from the source: enabling VPN service affects the network performance of the system, and only administrators can install and set up VPN Server.
Sources used: [11], [16]