DaemonUmbra

Please provide debug.log (more info on where it is and how to provide it in my signature below, just expand the spoiler)

This log shows the server taking a full minute to run a single game tick, and given how many mods you have there I'm not sure I'm surprised. Is this a published modpack or mods you put together?

1.8 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

You don't open the installer, you run it. If Java is installed, it should handle running the jar. However, if the jar is being opened by a program like winRAR, try Johann Löfflmann's JarFix utility to fix the file association.

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One of your coremods is fucking up, remove everything mentioned to have a coremod or mixin

The JVM arg doesn't fix it, we need to wait for either Apple to provide backwards compatibility with M1's or GLFW, LWJGL, and Mojang to accommodate the API changes in the M1

Your copy of ftbchunks may be corrupted, otherwise something is messing with Mixin's ability to read ftbchunks' mixin config

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support. The fact that you don't want to move past a certain mod does not change the rules.

That's not debug.log

Please provide debug.log (more info on where it is and how to provide it in my signature below, just expand the spoiler)

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Remove Optifine

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The root of it is GLFW using an API that is no longer exposed on M1's, so either Apple needs to implement a backwards compatible API or GLFW needs to update, and if GLFW updates LWJGL would need to update, and then Mojang would need to ship the updated LWJGL

If you have the same problem did you see the original answer?

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1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

What do you mean by "it does nothing"?

It's just your GitHub Pages url backwards with the mod name on the end, for example mine would be io.github.daemonumbra.modname

Check the world save for serverconfig, clear that folder too

Have you changed any configs? If not, delete every config.