Standard server: it is an ordinary VPN server, which can encrypt your Internet communication and replace your IP address.

Double VPN is a privacy solution that sends your Internet traffic through two servers and then encrypts it twice. Only OpenVPN (UDP) and OpenVPN (TCP) protocols are valid.

Onion over VPN is a privacy solution that can be transmitted over the onion network on the VPN server. More can be found in this place.

Proprietary IP server: a server used by users who have purchased their proprietary IP. Only OpenVPN (UDP) and OpenVPN (TCP) protocols are valid.

Obfuscator: it can bypass the restrictions of the Internet, such as network firewall. It is recommended that you use those countries with restrictions.