To demonstrate capabilities of QuickOPC, some OPC server is needed. Most examples use an OPC UA Sample Server provide by OPC Labs (based on OPC Foundation sample server) that is available over Internet. The server can be accessed on opc.tcp://opcua.demo-this.com:51210/UA/SampleServer, http://opcua.demo-this.com:51211/UA/SampleServer or https://opcua.demo-this.com:51212/UA/SampleServer (these are so-called Discovery URIs).
Note that if there is a firewall between the client machine and the server, it needs to have the corresponding ports (in the above example, 51210, 51211 and 51212) open for outbound traffic.
The demo application and the examples are designed to connect to the OPC UA Sample Server in its default configuration. In fact, some very simple examples connect to just one OPC node. For example, a dynamically changing double-precision value has node Id "nsu=http://test.org/UA/Data/;i=10854". You can either call the browsing methods to obtain other node Ids together with their descriptions, or you can simply borrow the node Ids used in our examples. There are various other OPC nodes in this server that you can use in your own experiments too.