AspNetCore.Docs/aspnetcore/signalr/diagnostics/logging-config.json

{
    "Logging": {
        "LogLevel": {
            "Default": "Debug",
            "System": "Information",
            "Microsoft": "Information",
            "Microsoft.AspNetCore.SignalR": "Debug",
            "Microsoft.AspNetCore.Http.Connections": "Debug"
        }
    }
}