NuGet Unable to load the service index for source Authentication failed

Since today for some reason I'm unable to connect to the NuGet package manager through Visual Studio.

[nuget.org] Unable to load the service index for source https://api.nuget.org/v3/index.json.
  An error occurred while sending the request.
  The underlying connection was closed: An unexpected error occurred on a send.
  Authentication failed because the remote party has closed the transport stream.

But I cannot get it to work again... Things I tried.

Delete NuGet.config
Clear NuGet cache
Disable TLS1.0 and TLS1.1 explicitly
Enabled TLS1.2 explicitly
followed the manual from nuget at https://devblogs.microsoft.com/nuget/deprecating-tls-1-0-and-1-1-on-nuget-org/
Different Visual Studios
Update to the latest Visual Studio 2019
Tried different TLS settings in the RegEdit for 1.0, 1.1 and 1.2. I don't have a TLS1.3 section yet.
I can browse to https://api.nuget.org/v3/index.json with chrome

TLS1.2 Client settings:

TLS1.2 Server settings:

Specs: Windows Server 2012R2, Visual Studio 2019

Also tried it on a different Windows Server 2012R2 machine and same problem

It is still working on my laptop with Windows 10.

Hopefully someone has an idea.

Thanks

Solution

Had exactly the same problem, running script from https://github.com/microsoft/azure-devops-tls12 and following instructions from it helped me. In my case it generated additional script file, after running that and restaring pc nuget was working once again.