Failed to login: The authentication servers are currently down for maintenance

Which servers are we talking about because there aren't any issues announced in the official website Xbox Status | Xbox Support? Also what device are you using?

Hello dear Gamer, first it's a pleasure to be able to help you today.

My name is Vinicius.

I am a gamer and independent advisor on the XBOX community platform.

Hey Oliver, how are you today, mate? Hope you're well.

So, have you tried to report this directly to Mojang, since the servers are down, they could shed some light into it.

Try to report here:

https://help.minecraft.net/hc/en-us/requests/new

Great! As I expected.

Then, for your teredo protocol qualify and your NAT would open, you will have to configure tour router like that Oliver.

If you're using a CONSOLE:

Call your internet service provider, and ask them to open the ports described below on your router.

Port 88 (UDP)
Port 3074 (UDP and TCP)
Port 53 (UDP and TCP)
Port 80 (TCP)
Port 500 (UDP)
Port 3544 (UDP)
Port 4500 (UDP)

Also ask to disable and then, enable it again the UPnP function and if you have a modem and a router the process has to be done on both devices.

Besides, ask them to put their console's IP in the DMZ zone configuration.

(To find the Xbox One IP address, press the Xbox button to open the dashboard, go to System > Settings > General > Network settings, then select Advanced settings.)
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If you're using a PC:

Call your internet service provider, and ask them to open the ports described below on your router.

Port 88 (UDP)
Port 3074 (UDP and TCP)
Port 53 (UDP and TCP)
Port 80 (TCP)
Port 500 (UDP)
Port 3544 (UDP)
Port 4500 (UDP)

Also ask to disable and then, enable it again the UPnP function and if you have a modem and a router the process has to be done on both devices.

Besides, ask them to put their PC's IP in the DMZ zone configuration.

To locate the IP of your PC: On the taskbar, select Wi-Fi network > the Wi-Fi network you're connected to > Properties.
Under Properties, look for your IP address listed next to IPv4 address.

Said that Teredo couldn't be qualificated

It worked, thank you so much, they realocated me to a public ip