react-native fetch throws "Network request failed" error just on Android Devices

I'm having the following problem with the API fetch on android devices:

Here is the fetching code:

login(user,password) {
    let query = oauthManager.loginUrl(user,password);
    console.log(query);

    return fetch(query)
    .then(response => response.json())
        .then(json => {
            //Error
            if( json.error ){
            console.log(json.error);
            return false
        }

        //Save and return token
        return oauthManager
          .saveOauth(json)
          .then(() => {
            return oauthManager.saveUser(user)
          })
          .then(() => {
            return oauthManager.getToken()
          })
          .then(token => {
            console.log(token);
            return true
          });
    })
    .catch((error) => {
      console.log(error)
    });
  },

The scripts works fine on ios devices. Any ideas on why is this happening?

Thank you very much