The first Elden Ring Nightreign network test "has ended" after a few disastrous hours, and "an additional network test is being considered" to make up for it

FromSoftware has apologized for the server issues during Elden Ring Nightreign's now-finished network test and is considering another session in the future, so you may still get to play the game ...
Shacknews

Elden Ring Nightreign devs apologize for issues during first Closed Network Test session

The first Elden Ring Nightreign Closed Network Test session has come and gone, but unfortunately it didn’t quite go as planned. Players were reportedly impacted heavily by server issues, to the point ...