Setup an IKEv2 server with strongSwan
IKEv2, or Internet Key Exchange v2, is a protocol that allows for direct IPSec tunnelling between networks. It is developed by Microsoft and Cisco (primarily) for mobile users, and introduced as an updated version of IKEv1 in 2005. The IKEv2 MOBIKE (Mobility and Multihoming) protocol allows the client to main secure connection despite network switches, such as when leaving a WiFi area for a mobile data area. IKEv2 works on most platforms, and natively supported on some platforms (OS X 10.11+, iOS 9.1+, and Windows 10) with no additional applications necessary.