There aren’t any settings specific to using the Vivaldi Upsampler as a Roon endpoint. Assuming the Upsampler and DAC are properly connected to each other with the serial cable then all of the default settings should be correct.
We don’t support configurations in which the dCS device is directly connected to a server on a “bridged” or private network. It might work that way, but there can be issues which may cause instability. Should a support issue arise the first thing we’ll ask you to do is to connect the Upsampler directly to the main network.