I have upgraded mongo to 4.2.6 and changed size of connection pool and it seems it helped:
taskExecutorPoolSize: 0
ShardingTaskExecutorPoolMinSize: 10
ShardingTaskExecutorPoolMaxConnecting: 5
I have upgraded mongo to 4.2.6 and changed size of connection pool and it seems it helped:
taskExecutorPoolSize: 0
ShardingTaskExecutorPoolMinSize: 10
ShardingTaskExecutorPoolMaxConnecting: 5