Several War Thunder players are reporting that they’re unable to log in or join matches. People are unable to view their purchases as well.
Players on Reddit report getting stuck at login screens, seeing a “Connection lost” message, or endless queues that fail to create or join battles. The problems seem to affect PC, mobile, and console users. Some joked about major outages frequently coinciding with major events.

According to real-time reports on Downdetector, there have been hundreds of reports of the issue over the past few hours, though they’re slowing down now.

Fortunately, Gaijin Entertainment has officially acknowledged the problem. In a statement posted on multiple social media platforms, the team confirmed that there may be difficulties in match creation, joining battles, etc. The company has assured players that the issues would be fixed soon and that the team is working to resolve the complaints.

Stable server operations are to resume “as soon as possible.” The graph on Downdetector suggests that the number of reports is already reducing, indicating that the company may have started fixing the issues already.
While no specific cause was mentioned in any of the statements, we’re assuming it’s because of backend updates or temporary connection glitches; these are common server-side issues (since the statement from the company says it’s a Server Maintenance Notice), and it’s not a user error. It’s not a problem with your internet connection or system, so there’s not much you can do from your side until it’s fixed directly.
You can just check back in a couple of hours and restart the client/launcher. Keep an eye out for posts from the official War Thunder account on your preferred media platform. Also, do let us know whether this issue has been fixed for you in the comments.