Hi guys! My problem is that when I try to connect to the Sandlot an error message pops up and says " failed to connect to the server Not authenticated with minecraft.net. Yes, I am on 1.12.2 and I'm currently using Java, I have tried deleting and adding the server back but it doesn't seem to have any impact. I logged my brother on and he was playing just fine on the same computer. Please help.
Log out of your Minecraft account and log back in, making sure you are using your new username (unless you have migrated to a Mojang account). The "Not authenticated with Minecraft.net" error occurs after you change your name.