I cant make a modded Server

I want to make a Server for All The Mods 6.
(I built the server, installed mine os, everyhting works fine with vanilla servers so there shouldnt be the problem)
So i download the Server Pack from Forge.

Unzipped it, put the files with filezilla into the server in /var/games/minecraft/servers/“Servername”

Then i got PuTTY, logged in, headed to the folder and typed in: chmod +x startserver.sh and then ./startserver.sh

Then it installs many stuff, i accept eula and then after its finished it says its restarting the server over and over. Wasnt able to type anything in so i closed it. All files seemed to be in the Serverfolder, such as mods, config, etc…

So i headed to mine os webpage, to the server, changed ram and now i dont know what to do…

i could load following runnable jars: (i dont select a profile, i just leave it blank)

  1. forge1.16.5-36.2.4. jar
    if i use this the server starts and then crashes immediately.

  2. minecraft_server1.16.5.jar (no profile selected as well)
    if i use this, it installs more stuff, prepares the world and the spawn area. The server works. But its a vanilla 1.16.5 minecraft server without mods…

  3. serverstarter-2.0.1.jar
    if i use this, the server starts but is also just a vanilla server.

What have i done wrong?

What java are you using? I have heard that java 11 works for 1.16.5. However, I have never been able to get it to work so I use java 8. I had a lot of issues starting a 1.16.5 server so if you want to check out the thread where ElPres and I discuss it that may help.