[My Server refuses to open due to mods (probably)]

I think I might of put this on the wrong for subforumn

[My Server refuses to open due to mods (probably)]

I've been struggling with making a modded Minecraft sever on 1.12.2 and long story short I think I nearly done it, but there aren't any tutorials or presubmitted questions regarding this topic which actually helped. 

I made a server, put the mods in, added a .bat for more ram, and now I have a problem with the server actually seeing the mods in the mods folder. if I start the game on the regular Minecraft server everything is fine; but all items don't work and I cant spawn in mobs from any mod. and if I start the game from the forge launcher, I get this message. 

 

C:\Users\Dominik15\Desktop\server>java -Xmx4096M -Xms4096M -jar server.jar nogui
A problem occurred running the Server launcher.java.lang.reflect.InvocationTargetException
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:567)
        at net.minecraftforge.fml.relauncher.ServerLaunchWrapper.run(ServerLaunchWrapper.java:70)
        at net.minecraftforge.fml.relauncher.ServerLaunchWrapper.main(ServerLaunchWrapper.java:34)
Caused by: java.lang.ClassCastException: class jdk.internal.loader.ClassLoaders$AppClassLoader cannot be cast to class java.net.URLClassLoader (jdk.internal.loader.ClassLoaders$AppClassLoader and java.net.URLClassLoader are in module java.base of loader 'bootstrap')
        at net.minecraft.launchwrapper.Launch.<init>(Launch.java:34)
        at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
        ... 6 more

C:\Users\Dominik15\Desktop\server>PAUSE
Press any key to continue . . .
 

so if anyone has any idea how to help it would be tremendously helpful, ive been rotting away in single player for so long I forgot that other life forms exist. Thank you and much love in advance.