JMeter Non HTTP response code: java.net.SocketException

Hello,

I am carrying out load testing with 250 users simultaneously.
I encountered the following problems:

Non HTTP response code: java.net.SocketException
And
Non HTTP response code: java.net.SocketTimeoutException

Concerning the first error, I read the following :
"This message usually occurs for high users load-test. It mainly occurs when the Port used to send request has crossed the maximum number of requests or when the request arrives when the port is occupied with many requests. Try configuring multiple ports at the server or run Jmeter in multiple instances with different ports."

We already have 4 injectors on which we have splitted the 250 users on the HTTP port 80. We need to keep the same port to test the same web site. Is there another port dedicated to the sockets or do we use the same port as the HTTP one ? if the port is different, is there a way to parameterize it? Is there a way to parameterize the number of sockets that can be sent to the port in jmeter.bat ?

Is " Non HTTP response code: java.net.SocketTimeoutException" a consequence of the " Non HTTP response code: java.net.SocketException" ?

Thanks in advance for your answers.

Regards

Sylvie CHABE