Thanks, Jonathan! :)

I think CORS and HTTPS were the main issues with this one.

I found that SignalR client doesn't accept that the request gets redirected, so if you are trying to hit HTTP and have HttpsRedirect middleware set, your SignalR client doesn't connect to your server.

CORS is funny because it also doesn't accept '*' for origins because it passes credentials through the connection.

And it took some research to proper find how to use IHubContext so I don't need to use the SignalR endpoint to send a request to the server.