Use custom registy, ideally from package.json

Question

In my package.json I have

"config": {
  "registry": "https://registry.example.net"
}

In order to use a local registry. If I execute yarn install --verbose though, I see yarn does not use this but uses its own registry:

Performing "GET" request to "https://registry.yarnpkg.com/ts-node/-/ts-node-8.3.0.tgz".

I managed to set the yarn registry manually

yarn config set registry https://registry.example.net

Even then, in verbose mode, it shows me that it is sending GET requests to registry.yarnpkg.com.

Also I need this to be configured so it also uses this registry on other dev machines and jenkins.

How can I get yarn to use my custom registry, ideally from a config file?