How to solve the stuck restore state when a C# project is being built

I’d like to have some C# dll project such as Mediapipe.NET or Math.NET Numerics to use them in a unity project as plug-in, not assets.

I downloaded the code from github and tried to built it, but when I use

dotnet build

in the project folder, the only thing that happen is that the build is stuck while restoring. When it time out, the error is : Unable to load the service index for source https://api.nuget.org/v3/index.json.

I tried with some known packages, to be sure it wasn’t the package I wanted that was the problem and it is the same. I also tried to delete the NuGet cache, still don’t work.

I saw on a forum it used to work with .NET 6 so I tried and it didn’t work like .NET 7 either.

It would be great if someone could help me :)

I use Ubuntu 22.04, and if you need more information, I’ll let you know.

Thanks