1.20.1 All The Mods 9 "The authentication servers are currently not reachable"

My server that me and my friends have been playing on for a few days are suddenly getting “Failed to log in"The authentication servers are currently not reachable” error.

We are playing on the 1.20.1 ATM9 modpack.

Things i’ve tried:

Restarting the server and pc’s

Flushing the DNS

Using alternate DNS’s

Checked the host file (nothing regarding mojang)

Logging out on our clients

Tried hosting a vanilla server and it works fine.

Tried hosting on my personal pc instead of the server

The server has access through the firewall, for both the ports and the javaw.exe

This is super strange. The server was functioning fine for 4+ days and randomly it happens. The issue has persisted for around 2 days now. I’ve also checked the server status, everything seems fine

I have no idea what to do now. Any help is appricated

The first I would check is wether the Minecraft Auth servers are available:

https://downdetector.com/status/minecraft/

or

https://minecraftstatus.net/

You also say that “Tried hosting a vanilla server and it works fine.”, has there been an update to your game version? It maight be that this update broke something. Did anyone add a mod?