Hello to everybody,

for several month we have a strange problem with the OPC UA Client SDK. Sometimes (not always) requested subscriptions are not transfered from the server to the client. To get more information about the problem, we started logging the network traffic between client and server with WireShark.
The observation shows, that in case of not working subscriptions the PublishRequest packages were not send from the client to the server.
Restarting the client helps.

Is there any idea, whats the reason for it?

Our test case:
1. Create a MonitoredDataItem with MonitoringMode: Reporting
2. Create a Subscription with a publishing interval of 5000ms
3. Add the data item to the subscription
4. Add the subscription to the UAClient
5. UAClient.connect()

You can also take a look in our WireShark observations. They are downloadable with the following links:

WireShark-Log with working subscriptions:
https://superus-my.sharepoint.com/:u:/g/personal/j_fischer_superus_de/ETR7yFWDSVNEoShtf7VtCacBSZDt8oC4sirLkIhqwxFPIw?e=icTHYW

WireShark-Log without PublishRequests (subscriptions not working):
https://superus-my.sharepoint.com/:u:/g/personal/j_fischer_superus_de/EeYAVupRrEZIq6Kjm7b-LokBLZ64_i4pRuIV04lCplW41g?e=1fcN1k

To reduce the high amount of logged data you can set a filter in WireShark with the following restrictions:
” opcua and ip.addr == 172.22.18.102 “
(172.22.18.102 is the IP Address of the OPC client, 172.17.20.5 is the OPC server)

Thanks for your help!