How to Reinstall Teredoby Dave Wilson
Teredo tunneling is a protocol that is part of the next generation TCP/IP protocol called "IPv6." Teredo tunneling enables devices using the IPv6 protocol to communicate through an IPv4 (the current version of TCP/IP) networks by creating a virtual IPv6 tunnel through an IPv4 network. Uninstalling firewalls or other security software may disable or uninstall Teredo Tunneling, which can cause the Windows Homegroup network feature to fail. Reinstall Teredo Tunneling in order to resolve the issue.
Boot the computer and then log in using the username and password of an account that has Administrator permissions on the Windows 7 computer.
Click the "Start" or "Globe" button in the lower-left corner of the PC desktop, then click the "Search" box and type "cmd." Right-click the command line icon that appears in the upper-left pane and then click "Run as Administrator" in the menu that appears.
Type "netsh interface ipv6 install" and press the "Enter" key. Then type "netsh interface ipv6 set teredo client" and press the "Enter" key. Reboot the computer and Teredo Tunneling will be reinstalled and enabled.