Allowing minecraft through a proxy server

Question

• System: Debian 10
• Minecraft version: 1.12.2 (Optifine)

My local internet connects via proxy and I'm trying to play on minecraft servers. I've already excluded port 25565 from the proxy server, but I still get an error when trying to connect to a server (mostly mc.hypixel.net). The error is:

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

This doesn't always pop up, 1/4 of the time I successfully connect to the server. I'm sure that it's not an issue with the authentication servers down, because when I refresh the number of players on the server, the number is sometimes going up. I want to know if there are any other ports / adreses that have to be unlocked in order for minecraft multiplayer to work.

Answer 1

Minecraft authentication on online mode servers (almost all of them, including hypixel) involves both the client and server going to different endpoints on https://sessionserver.mojang.com/ to verify the legitimacy of the user.

Specifically, the client goes to https://sessionserver.mojang.com/session/minecraft/join.

Depending on what your proxy does, this may be the reason why you're having issues, and you may want to whitelist this host too. You can read more about these endpoints here.