Looking at the documentation page for Xamarin.iOS CFStream here:

https://learn.microsoft.com/en-us/dotnet/api/corefoundation.cfstream?view=xamarin-mac-sdk-14

Apparently this class is deprecated, but it's not clear what Microsoft is telling you to use instead (N:Network APIs).
Following the link only leads to a search across the whole site for the word "network" and a search engine produces similarly vague results.

I'm trying to exchange a few bytes with a device that's already connected to the iPad via a local WLAN connection.