Teredo played an important role in the transition from IPv4 to IPv6. Although it's no longer widely used today, its legacy lives on:

Teredo is a networking protocol that's used to establish secure communications between clients and servers, and to facilitate conn... Microsoft Learn Unlock IPv6 with Teredo: Bridging IPv4 for Next-Gen Internet - Lenovo Teredo provides IPv6 connectivity by encapsulating IPv6 packets within IPv4 user datagram protocol (UDP) packets. Lenovo Teredo Tunneling Pseudo-Interface (Туннельный адаптер Microsoft ... Teredo Tunneling Pseudo-Interface (Туннельный адаптер Microsoft Teredo) ... Здравствуйте... Очень беспокоит Teredo Tunneling Pseud... Microsoft Learn Teredo Tunneling Pseudo-Interface Adapter Missing - Microsoft Q&A Oct 6, 2018 —

The is a Microsoft transition technology designed to provide full IPv6 connectivity for hosts that are on the IPv4 internet but lack a direct native connection to an IPv6 network.