I was following along with this guide, but as you can see, it's a bit old. Namely, it's for 1.15.2. Now, it seemed to be working all the way up to the very end:

 

Quote

package com.arnox.exmod.events;

import com.arnox.exmod.ExampleMod;
import com.arnox.exmod.commands.ClientTele;

import net.minecraftforge.eventbus.api.SubscribeEvent;
import net.minecraftforge.fml.common.Mod;
import net.minecraftforge.fml.event.server.FMLServerStartingEvent;

@Mod.EventBusSubscriber(modid = ExampleMod.MOD_ID)
public class CommandEvents
{
    @SubscribeEvent
    public static void onServerStarting(final FMLServerStartingEvent event)
    {
        ClientTele.register(event.getCommandDispatcher());
    }
    
}

Eclipse says the bolded method is undefined for the type FMLServerStartingEvent.

Use RegisterCommandsEvent.

1 hour ago, poopoodice said:

Use RegisterCommandsEvent.

That got it to run. Thanks!