Can not establish connection to OPC UA server

From the screenshot I can see that your server doesn’t have the “Server” object and other mandatory stuff under it. It needs to have those server capabilities etc. in the hierarchy. I don’t know anything about this specific Python library, so you’ll need to research how to fix that yourself.

The GitHub issue I linked is about defining these server capability objects that VC expects each OPC UA server to have.

Also see this other topic about the same issue.