Rainbow Six Siege won't connect to Wi-Fi, what to do?

Since Operation Shadow Legacy was released for R6, the game doesn't connect to Wi-Fi and shows offline all the time - Trying to reconnect.

I reconnected to the Wi-Fi several times, restarted the Wi-Fi router several times, restarted my Xbox several times and of course the game itself. I deleted my Mac address and other things I found in Youtube tutorials.

Unfortunately, nothing worked and that's why I'm desperately asking if anyone has any experience and help at hand.

Have you ever tried a LAN cable?

I've already thought about it, but it shouldn't be because everything always worked before