Setting up L2TP With IPsec (Support and Recommended for Remote User Access
For Site to Site - Peplink to Peplink appliance use the Wizard and use the Peplink (PepVPN) protocol.
PPTP is no longer recommended due to associated security concerns, as a result Apple products no longer support PPTP. Setting up L2TP is the preferred method for remote user access (VPN). You can find the associated setup documentation in the following thread. I hope this helps.
Setting up Your Peplink Device
On Balance models, navigate to Network > Remote User Access.
On MAX models, navigate to Advanced > Remote User Access.
Enter your preshared key in the Preshared Key text area.
In the Listen on section, select the LAN ports that you want the L2TP server to pay attention to. Be sure that at least one of the LAN ports have a public IP address.
Under the User Accounts section, enter the Usernames and Passwords for each client who will connect to the VPN. For bulk entry, click the (?) logo to enable pasting directly from a CSV file.
Setting Up Your Android Device
Notice: VPN configuration for Android varies depending on model. If in doubt, please refer to your device documentation.
Open your VPN settings page and tap the + button to add a new VPN profile.
See screenshots and stet though process here: