Issue: IEC-104 Server enters repeated connect/disconnect loop after manual client reconnect

[innovationshkrp]

When using the MZ Automation IEC 60870-5-104 multiple client, the server enters a continuous connect/disconnect loop after a client is manually disconnected and reconnected.

The IEC handshake (STARTDT act/con) completes successfully every time, but the connection is closed a few seconds later, and the client reconnects again with a new TCP port. This repeats indefinitely.

Example log pattern:

Client connected
STARTDT act
STARTDT con
Client disconnected
Client connected (new port)
STARTDT act
STARTDT con
Client disconnected
.....

Expected Behavior:

• After a manual disconnect, the server should fully clean up the IEC session
• On reconnect, the client should establish a stable, persistent connection
• No repeated connect/disconnect loop should occur

[juwiefer-btc]

You do not describe which client disconnects.

I guess that you use SINGLE_REDUNDANCY_GROUP, which only allows one client with a STARTDT. In this case, a STARTDT on one client leads to a STOPDT on the former active client. Some clients react with a FIN/disconnect to a spontaneous STOPDT. If this is the case, switching to CONNECTION_IS_REDUNDANCY_GROUP might help.