1. You are hooking to clientConnectionMonitoring.ServerConditionChanged. But you did not describe whether there are interesting events coming in. That is, when the problem occurs, does the "server condition" change, or not? Is it "connected" at that time, or at some other status?
Answer, this one code always shows as connected, only first time when i run this code, it shows as disconnected and later it always shows connected.

2. Please post here the code of your handler of DataChangeNotification (or the basic skeleton of it). What I am looking for is whether your error handling code is correct.
Answer, I am attaching the complet e code of form code behind file for further clarification.

We have been running and using QuickOPC client in our C# program to read necessary tags and capture some updates.
We have few concerns related to the OPC lab C# NuGet component which we are using.

We have EasyUAClient client component attached to the DataChangeNotification event in C# program.
And when we track changes based on one tag using DataChangeNotification, we notice that periodically, it stops detecting the change of the tag and the program freezes.
We need to know what is missing to track that periodical change.
This program behavior of non-detection happens only after the when program runs successfully for few hours. Then in such case, once we restart program, everything works fine.
We are running OpcLabs.QuickOpc of version 5.63.246.

Please find code snippet as below:

var client_qc8 = new EasyUAClient();
IEasyUAClientConnectionMonitoring clientConnectionMonitoring = client_qc8.GetService<IEasyUAClientConnectionMonitoring>();
if (clientConnectionMonitoring is null)
{
Console.WriteLine("The client connection monitoring service is not available.");
WriteText($"The client connection monitoring service is not available.");
return;
}

clientConnectionMonitoring.ServerConditionChanged += clientConnectionMonitoring_OnServerConditionChanged;
client_qc8.DataChangeNotification += UA_MultiDataChange_Notification_qc08;
client_qc8.SubscribeMultipleMonitoredItems(new[]
{
new EasyUAMonitoredItemArguments(null,url, “sometag”,1000),

});