massive client crash

i have been battling a problem for months with not much improvement. here is what I’m dealing with

when this happens everyone on the server crashes ( people joining are not affected)

so far i have been able to cause this to happen on purpose by getting 2 zombies stuck in each other and then killing them with an explosion. so far i have used nextbots “is stuck” to remove zombies that get stuck as well as prevent them from spawning on eachother. this decreases the times we all crash but the problem still exists.
any ideas on how to resolve this problem?