Sure, here’s a rephrased version suitable for posting on Stack Overflow:

I’m encountering an issue while load testing my Node.js Sequelize PostgreSQL application running on an NGINX server using JMeter. When I set 1000 threads with a 1-second ramp-up time, everything runs smoothly. However, when I increase the load to 10,000 threads with a 10-second ramp-up time, some calls fail with errors such as “connection refused,” “connection timed out,” or “failed to connect to server.”

To troubleshoot, I performed the same load test directly on the NGINX API without involving Node.js. Surprisingly, I still encountered similar issues, even though NGINX returned a 200 status code.

I suspect there might be a misconfiguration in my NGINX setup. Any insights on how to diagnose and resolve this issue would be greatly appreciated.