Minecraft: I can't connect to the server of my friend

Well, it has to be since others can join while I cant.

Hello Stanford,

If all of them have a strict NAT they will be able to join each other. This would also prevent you from joining. Try rebooting your network hardware. Also, ask your friend the one you trying to connect to check their NAT to see if it is open.

Thanks,

Brad

The NAT from your Network and the your friend network is all open?

I would recommend power cycling the Xbox by holding down the power button for 10 seconds and once the console shuts down unplug it for 2 minutes that should hopefully fix the issue

There are a few things that can be wrong here. First, if other people are joining, then NAT is fine on his end since NAT is Private IP to Public IP translation (actually it can do more than that but that is another discussion). Second, validate the port
you are connecting on when using his public IP Address. That could be the problem as connecting to the wrong port will result in a failed connection. Next, are others that are joining outside of his local area network? If they aren't, they are on a LAN
and he may not have his IP properly port forwarded so that you can connect. I can help with port forwarding in general if this is a problem assuming he has access to his router, I'm a network engineer by trade.

Other than that, it is definitely something on the server side. If the Minecraft server hosted on his local computer or does he have another dedicated box running the Minecraft server? A firewall may be misunderstanding your specific connection and rejecting
it on the attempt. Only way to know is for him to check the logs of the Minecraft server. It should show you attempting to connect if everything is gravy.