About Unet Match Maker servers ("localhost" and "Staging")

Hello, I found this code for the NetworkManagerHUD to can make my own HUD, and I saw in the Match Maker section 3 values:
https://bitbucket.org/Unity-Technologies/networking/src/2bdd9961092c4a73443c09694cff5dde9e56f9f1/Runtime/NetworkManagerHUD.cs?at=5.4&fileviewer=file-view-default

if (GUI.Button(new Rect(xpos, ypos, 200, 20), "Change MM server"))
                    {
                        m_ShowServer = !m_ShowServer;
                    }
                    if (m_ShowServer)
                    {
                        ypos += spacing;
                        if (GUI.Button(new Rect(xpos, ypos, 100, 20), "Local"))
                        {
                            manager.SetMatchHost("localhost", 1337, false);
                            m_ShowServer = false;
                        }
                        ypos += spacing;
                        if (GUI.Button(new Rect(xpos, ypos, 100, 20), "Internet"))
                        {
                            manager.SetMatchHost("mm.unet.unity3d.com", 443, true);
                            m_ShowServer = false;
                        }
                        ypos += spacing;
                        if (GUI.Button(new Rect(xpos, ypos, 100, 20), "Staging"))
                        {
                            manager.SetMatchHost("staging-mm.unet.unity3d.com", 443, true);
                            m_ShowServer = false;
                        }
                    }

-The “localhost” server don´t use bandwich from Unity servers (and don´t cost money and CCU)? it is free for us using this server configuration?.

-What is the “Staging” server?.

Thanks in advance.

nobody knows?

I know this is an old post, but it’s a good question. Here is the answer quoted from the docs (the link is at the bottom):

Change MM Server
This button is designed for internal use by Unity engineers (for testing the Multiplayer service). It reveals buttons which assign one of three pre-defined URLs to the MatchMaker Host URI field in the Network Manager - “local”, “staging” and “internet”. However, the “local” and “staging”** options are only intended for internal use by Unity engineers, and not intended for general use.

If you select the “local” or “staging” options, your game cannot connect to Unity’s Multiuser Service. Therefore you should always make sure this option is set to “internet” (which is the default).

https://docs.unity3d.com/Manual/UNetManagerHUDMatchMakerMode.html