Ask about discarded requests

Hi everyone,

I have 5 test steps, and run a load test ok (no errors) with 100 threads. But, when I try with 300 threads, I got many errors (1740 errors, greater than number of connections: 1441), I think it is because of there are many discarded requests (with timeout reason) as the below images.

I don't know why and how discarded requestes happen and how to change my test case config for testing properly and no more discarded requests ?

Can you help me ?

Many thanks !