SignalR in Delphi or C ++ Builder

I need to send data in real time between Delphi / C ++ Builder applications hosted on different PCs not connected on the same local network, only using the internet.

My first approach was obtained with DataSnap REST server, but this is not practical due to proxy and router issues. The configuration was too complex for the users, plus some people didn't want the web server running on their machines by opening the appropriate ports.

My second approach is to use a server in the middle. I am testing SignalR technology which seems to fit very well. It's solved well for C #, but I can't find any information about VCL, Delphi, or C ++ Builder.

Is there any library or do I need to work from scratch via WebSockets?

Is there another way to link VCL applications that run on separate computers that are only connected to the Internet?