PPTP. A consortium of vendors, including U.S. Robotics, Ascend Communications (now part of Lucent Technologies), 3Com, and Microsoft, developed PPTP. VPN software implementations are more likely than hardware implementations to use PPTP, although some VPN hardware vendors (e.g., Lucent in its MAX and Pipeline communication products and Nortel in its Contivity products) use it. PPTP software implementations can't handle high volumes of traffic, but PPTP hardware implementations can. PPTP 1.2 had major flaws, but version 2.0 fixed most of the problems. However, even this version 2.0 as Microsoft has implemented it is weak cryptographically because it still relies on the user's password to generate keys. In addition, PPTP's design and heavy promotion by a few large vendors such as Microsoft have made it suspect in some quarters.
They even offer the most generous simultaneous connection count, with six simultaneous connections through their network, where everyone else offers five or fewer. NordVPN's network isn't as large as some of their competitors, so if you're trying to obfuscate your tracks, you might want a company with more servers. Otherwise, this company is clearly providing a winning offering.