Event Log shows:

Communication link failure - Native Error 14503

TCP/IP Initialization Error:

MessageId=LIPT006I, Feedback=10048, ReturnCode=8
 &OSMSG=10048,&ADDR=nnn.nnn.nnn.nnn;1364.

The port 1364 is in use by another custom script, which emulates a listener on port 1364. This script was implemented during phase of server installation and needed for testing firewall rules without a running Sterling Connect:Direct installation. It gets started automatically during restart. It was neither set to only start manually nor removed.

OSMSG= Operating System Error Code.

WSAEADDRINUSE
10048 (0x2740)

Only one usage of each socket address (protocol/network
address/port) is normally permitted.

LIPT006I has the following meaning and structure

The call to bind() failed. OS message=&OSMSG. Addr=&ADDR.

A call to bind() failed to bind a socket to an address.
The port may be in use by another application, or may not
have timed out from a previous C:D session.

The system error message should provide further information

1364 and 1363 are reserved ports for Sterling Connect:Direct. These are the default ports. No other application should use these ports.
Check your server start procedure on what gets started automatically during restart. Identify which other application is using port 1364. Stop this application or reconfigure it to use a different port.
If you run Sterling Connect:Direct with ports other than the defaults, ensure that these ports do not get used by another application. On a stopped node, you can find the ports via CDAdmin, right mouse click on node name, Initialization Properties, API and TCP/IP.