Sometimes in new versions signalrwe need to work on old code and old versions and this is very troublesome. The link below with sample code can be a good guide for this type of problem.

var connection = new signalR.HubConnectionBuilder()
            .withUrl(ArianCore.GlobInfo.ApiUrl + "apiHub?", {
                 headers: { "token": getToketAuth() },
                transport: signalR.HttpTransportType.LongPolling
            }
            )
            .build();

https://learn.microsoft.com/en-us/aspnet/core/signalr/configuration?view=aspnetcore-8.0&tabs=javascript#configure-additional-options