MLC OPC UA issue from WinCC

A customer is updating an existing press line and the update changes include switching from OPC-DA to OPC-UA.  Their MLC's symbol file is built and loaded with the appropriate variables.  They can browse the variables from their MLC (14v20) with UA Test and UAExpert successfully.  When they try to browse the symbols with their Simatic WinCC tool they see the end point and connect to it, but then it shows disconnected and they can't browse the symbols.  They would like to maintain and use the connection without being disconnected.

Best reply by NoRisk4Project

Hello,
which endpoint is used by UA Expert and which by WinCC? As already mentioned, a not supported identity token or security policy could lead to refusing the connection. Do you get any (error / warning) message inside the WinCC tool?
A WireShark trace would be very helpful to see who (server or client) rejects the connection and why.

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