Update 2018-09-21:
We are progressing well a Server Lag issue, and have our first change in test at the moment. We’re confident this will improve server performance and reduce the chance of the server lagging. While we wait for these improvements to make it into the Live version we are going to reduce the number of players allowed on each world a little. This will reduce the likelihood of server lagging, and so make everyone’s experience better at the expense of some worlds filling up at peak times. Whilst not being able to get onto a world is frustrating, we feel that everyone on a world having a more consistent experience is a price worth paying.
This is a temporary change and we will increase the number of players allowed as soon as we are confident that performance will be consistent. To help spread the demand on servers during this period we are going to add some new worlds for you to explore.