I have a reason to use SignalR in Unity, I have decided to go with Microsoft.AspNetCore.SignalR.Client from NuGet.
I've tried a package Nivot.SignalR.Client.Net35 but it uses AspNet.SignalR.Client which is not used anymore, I have created everything I need on my WebApi solution using Microsoft.AspNetCore.SignalR, then I have changed in my Unity project in PlayerSettings Scripting Tuntime Version .NET 4.x Equivalent and Api Compatibility Level to .NET Standard 2.0, which is compatible with AspNetCore.SignalR.Client.
But after I install the package in visual studio while editing scripts and I try to use it Visual Studio keeps calm, but Unity says That the namespace Microsoft.AspNetCore.SignalR.Client doesn't exists. I have read that I have to copy them to a folder in the Assets folder, so I did it, and then Unity said "Unloading broken assembly Assets/Packages/Microsoft.AspNetCore.SignalR.Client.dll, this assembly can cause crashes in the runtime" and it doesn't work.
I've lost my hope. But then I remembered that there is Stackoverflow, so now I hope that someone here can help me. Thanks.