I am running the latest build (1803) for Windows 10 Pro and when launching the Xbox app then the server connection will indicate it is blocked even though there are no indications what is causing the fail.
I am running Norton Security and a Netgear Blackhawk router and in either case I have added ports for Teredo to forward, along with disabling/uninstalling my firewall and nothing I have tried has been any success.
When I review the hidden items within Device Manager it does not even show Teredo, yet from the command line it shows its working (as shown below)
I have indeed tried Microsoft however they are not helpful at all, as they are just reading from a script, and honestly when someone asks if my Internet connection is working when I am in a chat window on the same computer then it does not give me much hope.
Personally I believe Microsoft broke something in the update however Windows 10 recovery does not provide an option to restore from a earlier build. However if anyone else has any feedback or suggestions it would be most appreciated.
C:\WINDOWS\system32>netsh interface teredo set state servername=win10.ipv6.microsoft.com
C:\WINDOWS\system32>Netsh Int Teredo Show Stat
Type : client
Server Name : win10.ipv6.microsoft.com
Client Refresh Interval : 20 seconds
Client Port : unspecified
State : qualified
Client Type : teredo client
Network : unmanaged
NAT : restricted (address)
NAT Special Behaviour : UPNP: Yes, PortPreserving: Yes
Local Mapping : 192.168.1.5:50548
External NAT Mapping : 188.8.131.52:50548