3429588 - SUM [Error ]: com.sap.engine.services.dc.api.ConnectionException: [ERROR CODE DPL.DCAPI.1144] Could not establish connection

SUM, As Java could not establish connection on P4 port.

P4 port correctly maintained in profile.

in SUM:
DEPLOYMENT_COMPONENTS:

com.sap.engine.services.dc.api.ConnectionException: [ERROR CODE DPL.DCAPI.1144] Could not establish connection to AS Java on [<host>:5xx04]. Connection refused: connect (local port 5xxxx to address 0:0:0:0:0:0:0:0, remote port 5xx04 to address <I/P> [host]). Check if the host and port specified.

in default trace:

[EXCEPTION]
java.lang.IllegalStateException: Incorrect usage of unregistered loader for operation [loadClass of javax.xml.bind.annotation.XmlAccessorType].
[This loader has been unregistered by thread:
Deploy Parallel Stop Thread 3 at 2024 02 04 21:18:47:227 as part of the following operation:
    |java.lang.Thread.getStackTrace(Thread.java:1661)
   
    --------------------------------------------------------------------------]
ClassLoader name: [sap.com/tc~brms~arch~jobs~ear]
Loader hash code: 3c675fc4
Living status: unregistered
Direct parent loaders:
   [system:Frame]
   [service:servlet_jsp]
   [service:ejb]
   [service:tc~je~scheduler~api]
   [library:tc~bl~logging~api]
   [library:tc~bpem~base~lib]
   [library:tc~bpem~bl~lib]
   [library:tc~je~archtech~api]
This loader has been unregistered and should not be used anymore. Remove all the references to classes loaded by this loader.
  at com.sap.engine.boot.loader.MultiParentClassLoader.throwIllegalStateException(MultiParentClassLoader.java:490)
  at com.sap.engine.boot.loader.MultiParentClassLoader.loadClass(MultiParentClassLoader.java:238)
  at java.lang.Class.forName0(Native Method)
  at java.lang.Class.forNameFW(Class.java:362)
  at java.lang.Class.forName(Class.java:355)

SAP NetWeaver 7.5

SUM, P4 port , connection, unregistered , classloader , KBA , BC-JAS-DPL , Deployment , BC-UPG-TLS-TLJ , Upgrade tools for Java , Problem