How do I achieve more than 500 concurrent users?

I had a JM Load test done and here are the results:
100 User Load has no issues. 500 User load in 50 seconds also has no issues but with 500 concurrent requests it generates error and refusing connection with the server.
My site is custom PHP with a MySQL database!

Are there easy ways I can achieve higher performance and concurrent users? I would like at least 5000-8000 concurrent users.
This is my server config:
VPS Server
• OS: Linux CentOS
• RAM: 2 GB
• Storage: 60 GB ‡‡
• Bandwidth:…
How do I achieve more than 500 concurrent users?

See original post by Brad77