limiting players joining if ping too high

I run an NS2 server and notice when people join with pings of 140 or higher the server will start acting funny to players with pings under 100. The players start warping and seems like the server is having sync problems. The more players with high ping that join the worse it gets.

when server is full (20 ppl) and pings are in double digits there are no issues.

Is there a mod that you can set a ping limit or the get auto kicked?