Xbox in Warzone as offline but console online?

I have a problem and I have installed Warzone on my Xbox. But when I open the game it says I'm offline and everything is not available.

What do I have to do?

Have you ever checked whether the Warzone servers are in maintenance work?

How do i check this?

Just google it. If that doesn't help, disconnect and reconnect the Internet. As the last step, reinstall it.