If you have installed the latest updates and do not have any problems with your internet connection, make sure that your antivirus software or firewall is not blocking the connection between the client and the server.
This setting may required to be done every time after an update depending on your antivirus.
Some antivirus has additional settings so make sure to check the antivirus's site for further help.
Additionally, add (or correct if it has already been added) the exception rule for WorldOfTanks.exe.
If you continue to have issues, try reinstalling the game client.
Note: Please take special care in steps 1 - 4, they are essential to this process.
Please follow these steps to ensure that you do a clean install:
1) Uninstall your currently installed client and delete the remaining game folder and its contents (the default location is C:\Games).
2) Click on your start menu and in the search/run box type "%appdata%" (without the quotes) and press enter, then in the folder that comes up we would like you to delete the wargaming.net folder. Please also delete your previously downloaded WoT installers.
3) Next, click on your start menu and in the search/run box type "%temp%" (without the quotes) and press enter.
4) Delete all of the files in your User's temp folder that comes up (some of the files will be in use by Windows and will not let you delete them, just delete the ones you can).
5) Download a fresh copy of our latest full client from the following link: http://worldoftanks.asia/en/content/docs/update/
6) Install from the game.
7) Launch/Run World Of Tanks and update the game to the latest version.