Product Information:

Product: Prosys OPC UA Simulation Server
Version: v5.6.0‑6
SDK: Prosys OPC UA SDK for Java 5.4.0‑201
License: Free license
Operating System: Windows (64‑bit)

During discovery registration, the server initially attempts to register using opc.tcp://localhost:4840, but the OPC UA stack automatically switches to an alternate endpoint URL using the machine’s fully qualified domain name (for example, opc.tcp://:4840). Despite successful TCP connections and completed handshakes, the discovery server immediately closes the connection, and the registration never persists.

Could someone let me know what’s going wrong here? Everything used to work in the previous version of the server. I am seeing the issue after the server version upgrade.

Here is the details from the server log:

02/26/2026 16:11:24.898 INFO [DiscoveryRegistrationTimer] – localhost/127.0.0.1:4840 Connecting
02/26/2026 16:11:24.908 INFO [DiscoveryRegistrationTimer] – Connected (non-reverse), handshake completed
02/26/2026 16:11:25.126 INFO [DiscoveryRegistrationTimer] – 11 Closed
02/26/2026 16:11:25.126 INFO [TcpConnection/Read] – localhost/127.0.0.1:4840 Closed (graceful)

…

02/26/2026 16:11:26.392 INFO [DiscoveryRegistrationTimer]
Using an alternate endpoint URL
‘opc.tcp://bgl7115win64.mathworks.com:4840’
instead of the requested ‘opc.tcp://localhost:4840’

…

02/26/2026 16:21:27.183 WARN [TcpConnection/Read]
Bad_SecureChannelIdInvalid (0x80220000)
“The specified secure channel is no longer valid.”

…

02/26/2026 16:56:26.442 ERROR
Failed to renew security token.
Bad_ServerNotConnected (0x800D0000)