Every 3 weeks on Tuesday mornings (from about 7.00 am GMT) the servers are shut down for maintenance. During this time, bugs are fixed on databases, the performance is optimized and updates are applied. You will be informed in the game about 1 hour before that the servers are shut down. This message can be found at the top left of your window on the UK server.

During this time, the servers are unreachable and you can not play. You can read the UK forum or US forum while the game is not available.

After maintenance, you can see details of any changes made to the game on the UK forum or US forum.