Teredo Cannot Start, State is Offline or Unable to qualify (Solved)
This tutorial contains instructions to resolve the following problems with the Teredo Tunneling Interface: "Teredo Cannot Start", "Cannot Enable Teredo Adapter, "Teredo State is offline", "Error: Failed to Open Tunnel Adapter", "Teredo Cannot Start: Code 10" (Windows10/8/7) & "Teredo is unable to qualify" at Xbox App.