Exclude nuget packages from source control - visual-studio-2017

Question

I want to exclude nuget packages from the source control, because we use our own custom packages and they change often so it generates too many unnecessary changes in the source control. Also because it seems to be the recommended way to work with packages and source control.
I followed the steps given at the link below, using the instructions with TFS:
https://learn.microsoft.com/en-us/nuget/consume-packages/packages-and-source-control
Automatic package restoration is enabled, but when I generate the solution, restoration fail because it try to restore Microsoft packages from our custom source instead of the nuget.org source, I don't understand why.
For example (sorry its in french):
La restauration des packages NuGet a échoué pour le projet PointOfSaleWebsite :
La version '3.2.3' du package 'Microsoft.AspNet.Razor.fr' est introuvable.
C:\Program Files (x86)\Microsoft SDKs\NuGetPackages\: Le package 'Microsoft.AspNet.Razor.fr.3.2.3' est introuvable dans la source 'C:\Program Files (x86)\Microsoft SDKs\NuGetPackages\'.
http://srv-tfs:8080/tfs/.../_packaging/.../nuget/v3/index.json: Le package 'Microsoft.AspNet.Razor.fr.3.2.3' est introuvable dans la source 'http://srv-tfs:8080/tfs/.../_packaging/.../nuget/v3/index.json'.
I tried to add this to the NuGet.Config, but still have the same errors:
<packageSources>
<add key="nuget.org" value="https://www.nuget.org/api/v2/" />
<add key="OurCustomSource" value="http://srv-tfs:8080/tfs/.../_packaging/.../nuget/v3/index.json" />
</packageSources>
I also tried to run this command in the package manager console:
Update-Package -Reinstall
It fails with this error:
Update-Package : Certains packages NuGet sont manquants dans la solution. Les packages doivent être restaurés pour générer le graphique de dépendance. Restaurez les packages avant d'effectuer des opé
rations.
Au niveau de ligne : 1 Caractère : 15
+ Update-Package <<<< -Reinstall
+ CategoryInfo : InvalidOperation: (:) [Update-Package], InvalidOperationException
+ FullyQualifiedErrorId : NuGetMissingPackages,NuGet.PackageManagement.PowerShellCmdlets.UpdatePackageCommand
Any idea why it try to restore from the wrong source ? or is it something wrong i'm doing to exclude packages from the source control ?

Answer 1

I read this: https://learn.microsoft.com/en-us/nuget/consume-packages/package-restore#build-time-restore-in-visual-studio
Step 4 especially pointed me in the right direction, it turned out that I only had by mistake uncheked the nuget.org source from the visual studio options !!
I apologize for not having seen it earlier ! I'm ashamed, such a waste of time :(