TileEntity

Use Java 17 instead of Java 21

Is there a logs-folder with a latest.log? If yes, add it here with sites like https://paste.ee/ Also make a test without the nogui entry

Make a test without modernfix

Add the lines of your start bat file

Somewhere in the Server settings / Aternos board or similar

1.20.6 requires Java 21 to work

Does the Server also have 8 GB?

Also make a test without the mod parcool

What modpack do you use and how much RAM do you have there? Maybe the modpack is too large for the given RAM

Remove the new mods one by one until you find the one, causing this issue

Is this the full crash-report?

Create a Forge 1.20.1 instance and make sure all mods are for 1.20.1

The last mentioned mod is immediatelyfast - make a test without this mod

Was the last added mod betterpingdisplay? If not, remove this mod

Maybe a conflict with AchievementOptimizer - make a test without this mod

Allocate more RAM to the server

Make a test with Embeddium instead of Rubidium

Remove the mod nvidium

Make sure you are using Java 17 Also check for the logs-folder for the latest.log and add it here

Make a test with another Launcher like MultiMC, AT Launcher or Technic Launcher

Backup your files and completely reinstall this modpack instance

Then I have no idea - report it to the creators

Are there other mods or just pixelmon?

Change -Xmx1G to -Xmx4G

Add crash-reports with sites like https://paste.ee/ Use a pre-configured modpack as working base - most of these already have a server pack The just add new mods one by one