I want to implement a SignalR Client in react.

I have a aspnet api wich provides SignalR Hub. With a C# SignalR Client i can connect with the hub and send+ receive messages. So it seems that the SignalR Service and CORS are correct.

But when i want to connect with react i get following error:

Debug: HubConnection failed to start successfully because of error 'Error: Unable to connect 
to the server with any of the available transports.
WebSockets failed: 
Error: 'WebSockets' is disabled by the client.
ServerSentEvents failed: Error: 'ServerSentEvents' is disabled by the client.
LongPolling failed: Error: 'LongPolling' is disabled by the client.'.

My react code:

import { HubConnectionBuilder,LogLevel,HttpTransportType } from '@microsoft/signalr';
import { getUserAccessToken } from '../auth/UserManager';

export function ConnectToSignalR(){
   return  new HubConnectionBuilder()
        .withUrl('https://localhost:18198/IIT/messagehub',options=> {
            options.skipNegotiation=false;
            options.transport = HttpTransportType.WebSockets;
            options.accessTokenFactory = ()=>getUserAccessToken();
        return options;})
        .withAutomaticReconnect()
        .configureLogging(LogLevel.Trace)
        .build();
}

export function startSignalRConnection(signalRConnection){
    if (signalRConnection) {
        signalRConnection.start()
              .then(result => {
                  console.log('SingnalR','Connected!');
    
                  signalRConnection.on('TimeWarningMessage', message => {
                     console.log(message);
                  });
              })
              .catch(e => console.log('SingalR Connection failed: ', e));
            }
        
}

Code is called in App.js (main component) of react app via useEffect hook once application starts.

What is ment by ‘ is disabled by the client’?
Is there a way those things can be disabled?
Browser i tested ist current version of Edge and Chrome, bothhave same issue.
Version of react package is 8.0.7 and in Backend on asp net core side, i am using NET8