Current/Peak/Limit queue length shows, in order:
The number of connections currently in the queue.
The largest number of connections that have been in the queue simultaneously.
The maximum size of the connection queue. This number is:
Maximum Queue Size = Thread Pool Queue Size + Maximum Threads + Keep-Alive Queue Size
Once the connection queue is full, new connections are dropped.
If the peak queue length, also known as the maximum queue size, is close to the limit, you can increase the maximum connection queue size to avoid dropping connections under heavy load.