The Nostalrius vanilla WoW servers made their return over the weekend under a new banner.
As was announced a couple of weeks back, the Nostalrius servers came back from the dead over the weekend. Of course, they weren't run by the same team. Instead, they were under the banner of the Elysium Project.
As you might expect, there was a flood of players trying to get into the servers, and with concurrent players capped at 5,000, queues were a common sight. Compounding the issue, the Elysium team said on Twitter that they were facing six concurrent DDoS attacks.
Dear community, we are working to address the lag and login servers. However, please be aware, we are undergoing 6 concurrent DDoS attacks.— Elysium Project (@elysium_dev) December 18, 2016
It looks like they've gotten those issues under control, as both the PvE and PvP realms are up now. According to the official timeline for the new server progression, the PvE server can look forward to the addition of Blackwing Lair and Patch 1.6 next month. The PvP server is a bit more advanced, with patch 1.9 (The Gates of Ahn'Qiraj) planned for launch in February.
I'd expect that these servers will continue to be busy throughout the holidays. There's still a "fresh-start" server planned for those who want to experience what the game was like at launch all over again. Of course all of this is contingent upon the continued existence of the servers, which in light of the fact that Blizzard already forced them to be shut down once, is up in the air.
If you want to try out Nostalrius for yourself, you can find more information over on the Elysium website.