According to Activision's Online Services page, Call of Duty: Vanguard and Warzone are experiencing connectivity issues on all platforms.
Activision is aware of issues that are affecting both Vanguard and Warzone, as well as Black Ops III PC on all platforms. The listed issues were apparently identified by Activision within the last hour and are currently being investigated.
Activision hasn't reported any issues with the BO4 connection on PlayStation 4 prior to the server outage.
On the Vanguard-specific service page, issues related to Vanguard have been removed from the general Online Services page, but Activision is still reporting a disconnect on all platforms for the game.
Although the developers are likely to be working on a solution, this will take at least a little time out of the Double XP week that began today for both weapons and the battle pass in Vanguard and Warzone.
Due to connectivity difficulties, the Call of Duty League Championship, the largest tournament of the year, is also delayed for more than an hour. The league appeared prepared to start the second match of the tournament at the time the servers were down.
This is a breaking news story, which may contain further details. Updates will be provided as soon as possible.