Back in July, Patch 11 hit Fallout 76 like a super sledge, breaking many of the things it was intended to fix. Players demanded a test server to prevent it from happening again, as seen in threads like this one on Bethesda's official Fallout 76 forum. And now those players are getting their wish.
"A Public Test Server (PTS) is currently in the works with the hope to get it up and running in 2020. Once we’ve figured out all (or most of) the kinks, we will be able to provide more details on our PTS and how you can participate."