The maxping stopped working a couple of months ago. Players with higher ping values than set are able to play on the server.
Because of this, there's been a huge increase in players whose ping is in the 300+ region, who we used to block out by setting maxping to 250. The majority of these players cheat via glitches or scripts, and we find we're having to ban on a daily basis.
Maxping is a staple piece of functionality for gameservers on any game, as it can help keep the quality of gameplay up by keeping out players with high pings and also be used as another level of protection against glitchers and scripters.