Steps to reproduce :

1) Download attached project " Teste.zip" and open in Unity.
2) Open scene main.
3) Build for windows standalone.
4) Press Play in Unity and launch built project.
Note: both shows same result - network is reachable.(see image attached "reachable.png").
5)Disconnect your machine from Internet.
Note: Built version shows same result as before while Editor shows that network is not reachable.("notReachable.png").

Expected result: Built version should say that network is not reachable when internet is disabled.

Actual result: When internet is disabled its still shows - network is reachable.

Tested versions: 5.2.4f1, 5.3.5p4, 5.4.0b22.