Xbox Multiplayer not working because of Teredo state

Hello, I've been playing Forza Horizon 4 (FH4 from here) the last couple days, waiting for a friend to get the new one so we could start together.
The Multiplayer of FH4 had previously not worked for me for over a year, so I was positively surprised to just find it working the other day.
Before, as well as from today, my Xbox Server Connectivity status is "blocked".
I'm not a total newcomer when it comes to tech, so I'll list a couple things that I think may be noteworthy.
1. I have reinstalled Windows 10 Home on my machine about 3 months ago.

2. I first started the game up again about a week ago. Initially I wanted to just drive around Solo again, but I just connected to the multiplayer regularly, so something must have changed for that to happen. I don't know what though.

3. I played the game fine yesterday, the 23rd. It's not working today.
My router performed an update in the early hours of the 23rd.

4. Even after the update, the Teredo blocking function in my router is still disabled, so Teredo should not be blocked by it.

5. My Teredo adapter states this when queried "netsh int teredo show stat":
---------------------------------------------
Type : disabled
Server Name : win1910.ipv6.microsoft.com.
Client Refresh Interval : 20 seconds
Client Port : unspecified
State : offline
Error : none

6. When I change my Teredo type to "enterpriseclient" with "netsh interface teredo set state type=enterpriseclient", the new output is:
---------------------------------------------
Type : enterpriseclient
Server Name : win1910.ipv6.microsoft.com.
Client Refresh Interval : 20 seconds
Client Port : unspecified
State : probe (primary server)
Client Type : teredo client
Network : unmanaged

7. In both cases, the Xbox Server connectivity remains Blocked.

8. Something curious I have noticed now as well as when I tried to fix this the last time: I can not find a Teredo tunneling adapter in my network devices. It is not listed, not even as disabled, as if it had been uninstalled.

9. However, not only is the Teredo tunneling adapter not in my device list, I also can not add it as legacy hardware.
When I go to the Microsoft tab in the "Install legacy hardware"-Window, there is no Microsoft Teredo tunneling adapter.

I do not know where to go with trying to fix this. I'm just hoping to get this running again before christmas so my friend and I can play FH5 together.

:)