Communication exception during 500+ concurrent requests

Hi, Was load testing against openldap (slapd-meta) where we were trying to submit 1000 concurrent bind requests. This was done using the JMeter load testing tool. In every run approximately only 420-430 bind requests are successful and remaining 500+ bind requests fail with "Communication Exception" error. We also tried with 500 bind requests and the result was somewhat same - 420 odd successful and 70-80 failed with communication exception. We have openldap 2.4.56 installed on a RHEL 8.1 host with 32GB memory and 8CPU. We have configured max open files for the slapd process to be 65K . Our requirement is to support 6000 concurrent requests at minimum. Is there any configuration that can be tweaked to support this amount of concurrent load ? I do see "olcConcurrency" & "olcThreads" set to 0 and 16 respectively. Should we be tweaking these to support the required load, if yes what should be the values for those ? Please assist. Thank you for your help !