Which plane is crashing?
Do you have enough CPU/Memory allocated to the system?
We have see this when the number of APs have exceeded the allocated CPU.
Number of APs/Number ofClients/Number of CPU Cores/Memory (GB)/HD (GB)
25/500/2/5/100
50/1,000/2/5/100
100/2,000/2/5/100
500/10,000/4/6/100