OK, so I have two computers. The first of the two is the server, a linux machine meant to be running the Minecraft server. The second of which is the Windows 10 client, trying to connect.
I'm using a file from here which is the .jar file for Spigot 1.7.10 R0.2 snapshot server. When running the server, getting past worldgen and the eula, on the Windows 10 machine it starts just fine and I can connect via Minecraft 1.7.10 and by entering 'localhost' into the address bar in Minecraft.
Yet when I start the server on the Linux machine, and type in the local address for it, I connect, (i.e. "Connecting to the server..."), and begin to login (i.e. "Logging in..."), and then I get an authentication error (i.e. "Authentication servers are down. Please try again later, sorry!").
Obviously I can ping the other computer, and it responds. I can also connect via SSH just fine. I've also tried just disabling the firewall on one, either, or both machines and that didn't help.
Why can connect when it is ran locally (on one PC), but get the authentication error when connecting over LAN? How can I fix this?