This article is relevant for all .Net products
The naming about the redundancy can be a bit confusing, we don't provide support for the server redundancy on the server side, but server redundancy on the client side - the client can communicate with a set of redundant servers.
Besides that, the SDK only supports the redundancy modes cold and warm.
The displayed enumeration displays all possibly existing redundancy types, but not all of them are supported.
The transparent redundancy mode is implicitly supported for the client, because this mode looks like a single server to clients.
The SDK provides only support on the client side to handle redundant servers.
The SDK does not provide support for redundancy on the server side, as all the sophisticated details depend on the application. (How to calculate the service levels? Shall the secondary server be started on a primary failure or is it always running? Is there data to be exchanged between the servers and how to exchange it?...).
But of course, it is possible using the OPC UA C++ SDK to build redundant servers.