We've temporarily taken the realm down on Xbox while we investigate an issue. We aren't yet able to provide an ETA on how long this will take. Our apologies for the inconvenience.
Unfortunately, in order to resolve the issue we've uncovered, we must execute a full Xbox realm rollback, bringing the servers back to the state prior to our most recent patch. This means that any progress gained within that hour will be lost.
We're expecting to bring the Xbox realm back up very soon. In the meantime, if you're interested to know what happened to cause this, we've posted more information here: https://www.pathofexile.com/forum/view-thread/3040872