OPC UA Timestamp issue for historical tags

I have an issue with historical tags, because time/date of the machine server keep changing. I read this article below:
"The nature of OPC UA Historical Access requires that a single timestamp reference be used to relate the multiple data points, and the may request which timestamp will be used as the reference. For the historical data nodes the SourceTimestamp is used to determine which historical data values are to be returned."

How can I set up the OPC UA in ignition to have a single timestamp reference for historical tags?