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OPCUA: Frequent connection drops

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24 Sep 2026 16:03 #14700 by support
Replied by support on topic OPCUA: Frequent connection drops
Hello,

some questions:

1) Case 1: Are you subscribed to something? Because if not, then disconnecting after HoldPeriod is the behavior by design.

2) Case 2: When you say "We have not had this issue before", what do you mean by "before"? Are you referring to a different QuickOPC  version, or is there anything else that has changed, or did it just start appearing without any change in the system you are aware of?

3) Case 2: The error says "{BadNoCommunication}. Server not responding to keep alive requests.". Therefore the first thing to is to check whether the server is responding to keep alive requests. We will need a WireShark log of the communication, and the corresponding log from the QuickOPC application, with timestamps attempting to correlate the two.

4) Case 2: Do you know if there is a high CPU load on the client or on the server, or the network is congested?

It would be also worth to set higher value to KeepAliveInterval in session parameters.

Regards
 

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24 Sep 2026 13:59 #14698 by Andriy
OPCUA: Frequent connection drops was created by Andriy
Hello,
Environment:
.NET Version: 10
QuickOPC Version: 5.84.374
OPC UA Server: custom implementation
We are experiencing intermittent communication interruptions with OPCUA servers.

Case 1: unexplained disconnected event
The Disconnected event fires without any apparent cause. Shortly after, communication is restored. This issue can be reproduced by delaying the data response from the OPC UA server for 5-6 seconds.
Workaround: Setting HoldPeriod to a large value mitigates this issue.

Case 2: BadNoCommunication Keep-Alive Failures
On a separate server, we experience frequent disconnections with the following error:
Code:
Error reported for OPC UA endpoint "opc.tcp://zzzz:62541". ConnectionState: Disconnecting. Error: "Opc.UA.ServiceResult=0x80310000" "OPC UA service result - {BadNoCommunication}. Server not responding to keep alive requests. + Some possible causes of this error are that the OPC-UA server is not running, or is not configured to listen on the specified port. Also, the network connection may be broken (cable unplugged?). + The client method called (or event/callback invoked) was 'ServerConditionChanged'." OpcLabs.EasyOpc.UA.UAServiceException: OPC UA service result - {BadNoCommunication}. Server not responding to keep alive requests. + Some possible causes of this error are that the OPC-UA server is not running, or is not configured to listen on the specified port. Also, the network connection may be broken (cable unplugged?). + The client method called (or event/callback invoked) was 'ServerConditionChanged'.
We have not had this issue before

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