Forza Horizon 4 Xbox Online Problem?

I haven't been able to join a session for several days. There's always an error message.

Thank you in advance

It seems to me as if you have the usual problem with the DNS server or the Teredo filter responsible for it.

If you play on the Xbox, you would have to go to the Internet settings, which is where I think a troubleshooting for the Xbox server should be, but it can of course also be wrong because I haven't used my One for several months.

If you have a FRITZ! Box modem (WLAN router), it may also be due to this.

If you do play on PC, just answer, I know my way around PC better than I do with Xbox.