SoftEther VPN Project develops and distributes SoftEther VPN. An Open-Source Free Cross-platform Multi-protocol VPN Program, as an academic project from University of Tsukuba, under the Apache License 2.0. SSL-VPN (HTTPS) and 6 major VPN protocols (OpenVPN, IPsec, L2TP, MS-SSTP, L2TPv3 and EtherIP) are all supported as VPN tunneling underlay protocols.
This post explains VPN protocols and how to choose the right one for the best. VPN Protocols: PPTP VS SSTP VS L2TP/IPSec VS IPSec/IKEv2 VS OpenVPN VS SoftEther VS WireGuard.