You may have trouble getting online today to play World of Warcraft or other games due to some trouble with Blizzard’s online service.

Battle.net is having issues that is preventing many people from logging into their accounts. This is preventing gamers from playing World of Warcraft, Hearthstone: Heroes of Warcraft, and other Blizzard games. The publisher says that it is a problem with its authentication servers, and it is looking into it.

“We’re aware of an issue that is affecting our authentication servers, which may result in failed or slow login attempts,” reads a notice on Battle.net. “We’re currently investigating the cause and will provide updates as they’re available.”

In addition to the server problems, Battle.net is busy and is placing new players into a queue before letting them log in. Current wait times vary from 15 to 20 minutes.

Downed servers made headlines over the holidays when a cyberattack took down the online services for Xbox and PlayStation. This prevented console gamers from getting on and enjoying big new releases like Far Cry 4 and Call of Duty: Advanced Warfare on Christmas Day and beyond.

The same group that took responsibility for assaulting Xbox Live and PlayStation Network previously claimed it took down Battle.net in October. We’ve asked Blizzard if today’s troubles are related to an attack, and we’ll update this post with any new information.