Hello.I agree that if it is actually possible to connect to the server (I am not sure about it - we would need a Wireshark trace), that

• QuickOPC should eventually make the reconnection, and
• The repeated Disconnected notifications are not by design (although by itself, I consider it a small bug)

The AI analysis is full of errors and makes little sense when compared with what the code actually does. It looks like that the AI misunderstood the purpose of the various timers involved. There might be *some* useful info in it, but it is hard to tell. The recommended AI solutions are mostly rubbish, they are either unapplicable or would introduce other bugs.

I need to reproduce the problem here in order to be able to make progress. Using the problem statement you gave to the AI, I made a setup consisting of a client program, and one local server, and one remote server. The code is attached. When I run the program, I disconnect the network cable from my computer to the network (= to the remote server), and I reconnect it back after some time. I got the expected behavior, i.e. QuickOPC reconnected to the remote server. 

Network cable was unplugged on 11:17:00
Network cable was plugged back in on 11:23:00
The output from the program is attached.

If you want this to go forward, you need to provide me with reproducible scenario. Questions:

1. Did I understand the scenario correctly, i.e. would *you* think that the provided program should manifest the problem, or not?
2. If I have understood it correctly, and you run the same program (you can change the server endpoints and node IDs to something else.), does it show the problem you reported?
3. If I have not understood it correctly, modify the program so that it shows the problem when you run it with your servers. Send me the modified program, and I will check if I can reproduce it here with my servers.

 

Hello.

We will review the information you provided. It will take some time. Will post here when we have an update.

Regards
 

 

Dear technical support:
I spent a lot of time talking to tokens and AI in order to understand whether the current problem can be located and solved, and also to enable QuickOPC officials to quickly understand the importance of this issue to my work. I am extremely eager to solve this problem and provide you with detailed AI analysis documents and solutions (AI provided ideas);

Problem description:
1) The infinite, high-frequency, and continuous disconnection after disconnection is unreasonable from the perspective of communication explanation. There must be a connection and then disconnection
2) The machine is manually powered off, disconnected from the network, or shut down. After 5 minutes, it can be restarted and restored to normal status, but cannot be successfully reconnected
Expectation: Could you please take a few minutes to review the document I provided (AI scanning conclusion and repair suggestions)

Dear technical support: wrote:

I suspect it may be a bug. I have been following this situation for about a year now, but when there is a 4051 error and reconnection fails; At the same time, there are a large number of disconnection logs, without reconnection attempts, constantly reporting disconnection, which is quite contradictory because there is no reconnection, only disconnection.

I suggest using AI to scan and analyze whether the situation I have reported exists~

Simon.Yu
vskysoft.com

Last reported bug and received version fix:
forum.opclabs.com/forum/search?searchuser=kong&searchdate=all&childforums=1&catids=9
 

Dear Support:

    After shutting down and restarting the machine, EasyUAClient client  cannot reconnect

1) Windows Server 2025 -Version 24H2 (OS Build 26100.1742),  .NET8.0 , QuickOPC 5.83.1043.1  (OpcLabs.EasyOpcUA.dll) 
2) 2023-03-02 16:53 report: Event Id: 4051 ,　"OPC_Srv_ConditionChanged.log"　batch disconnect log  ;
3) EasyUAClient　parameter: 
    easyUAClient = new EasyUAClient() {};
    easyUAClient.IsolatedParameters.SessionParameters.HoldPeriod = 15000;
    easyUAClient.IsolatedParameters.SessionParameters.RetrialDelay = 60000;
    EasyUAClient.AdaptableParameters.SessionParameters.HoldPeriod = 15000;
    EasyUAClient.AdaptableParameters.SessionParameters.RetrialDelay = 60000;
    EasyUAClient.SharedParameters.EngineParameters.RetrialDelay = 60000;  
4)This issue has been receiving feedback all along and is an old problem，Based on our previous feedback, we have updated the driver to the latest version as per your request
5) target IP :10.10.100.114  cannot reconnect; The client is running normally and collecting data normally
6) Why does the target IP always appear as'Disconnected ,opc.tcp://10.10.100.114:4840'  in   OPC_Srv-ConditionChanged. log'
7) Why didn't you try reconnecting?  Two log documents are attached

The above situation has been troubling my project, looking forward to your reply

2023-03-03 14：20 

---

Expand info.:

2026-03-02 16:53:50.178,EvId:4051,Warning The OPC-UA client session with connect sequence number 12 on endpoint URL "opc.tcp://10.10.100.114:4840" has encountered a publish error with code 0x80260000 for
 subscription ID 0 and sequence number 0. The error might be from the Publish or the Republish service. Further publish errors with this code on this session will not be logged. 
Service result: BadSessionClosed 'BadSessionClosed'.</value>

2026-03-02 16:53:50.197,EvId:4024,Information The OPC-UA client session with connect sequence number 12 is disconnecting from endpoint URL "opc.tcp://10.10.100.114:4840". Affect SDK engine: no.
2026-03-02 16:53:55.491,EvId:4051,Warning The OPC-UA client session with connect sequence number 12 on endpoint URL "opc.tcp://10.10.100.114:4840" has encountered a publish 
error with code 0x80860000 for subscription ID 0 and sequence number 0. The error might be from the Publish or the Republish service. Further publish errors with this code on this session will not be logged. 
Service result: BadSecureChannelClosed 'BadSecureChannelClosed'.</value>

 
2026-03-02 16:53:50.197 OpcServer StatusChanged:【Disconnecting, opc.tcp://10.10.100.114:4840】
2026-03-02 16:53:50.232 Disconnecting ,opc.tcp://10.10.100.114:4840
2026-03-02 16:53:50.237 Disconnected ,opc.tcp://10.10.100.114:4840
2026-03-02 16:53:51.471 Disconnected ,opc.tcp://10.10.100.114:4840
2026-03-02 16:53:51.518 Disconnected ,opc.tcp://10.10.100.114:4840
2026-03-02 16:53:55.494 Disconnected ,opc.tcp://10.10.100.114:4840
2026-03-02 16:53:55.539 Disconnected ,opc.tcp://10.10.100.114:4840
....
....
2026-03-02 16:54:01.524 Disconnected ,opc.tcp://10.10.100.114:4840
2026-03-02 16:54:01.742 Disconnected ,opc.tcp://10.10.100.114:4840
....
....
2026-03-02 23:59:10.985 Disconnected ,opc.tcp://10.10.100.114:4840
2026-03-02 23:59:11.025 Disconnected ,opc.tcp://10.10.100.114:4840
2026-03-02 23:59:11.478 Disconnected ,opc.tcp://10.10.100.114:4840
2026-03-02 23:59:11.527 Disconnected ,opc.tcp://10.10.100.114:4840
2026-03-02 23:59:11.956 Disconnected ,opc.tcp://10.10.100.114:4840