Please refer to the following KB articles.
System Requirement for SpeedFusion Configuration
Configuring SpeedFusion Site-to-Site VPN for Star Scenario (It’s not a star scenario in your case, but this is the image of how to set up Peplink/Pepwave S2S VPN.)
Can I route Internet traffic to VPN peers? (You can specify only TCP:80 and 443 for VPN tunnel.)
Hope this clarifies the matters.