Board Thread:Modded Server Technical Support/@comment-2606:6000:D8D2:4300:870:8D67:37E5:7D3C-20171209192142/@comment-25330335-20190815141836

If it was the official server, I believe that they sometimes use a whitelist to bring the server down for maintenance, instead of shutting it down completely. That way the admins can still log on to do stuff.

Please keep in mind that I am a wiki admin, not a server admin, so I have no idea if this is actually what happened to you, nor am I a reliable source of information when it comes to servers. Generally if you have server related questions, you should post on the appropriate server's Facebook page or ask in their official discord, or however else that community connects outside of minecraft.