Not enough prestart jobs at server

If the number of prestart jobs associated with the TCP/IP server is limited by the QRWTSRVR prestart job entry of the QSYSWRK subsystem, and all prestart jobs are being used for a connection, an attempt at a new connection will fail with these messages.

CPE3426: A connection with a remote socket was reset by that socket.
CPD3E34: DDM TCP/IP communications error occurred on recv() — MSG_PEEK.

You can avoid this problem at the server by setting the MAXJOBS parameter of the Change Prestart Job Entry (CHGPJE) command for the QTWTSRVR entry to a higher number or to *NOMAX, and by setting the ADLJOBS parameter to something other than 0.