The mod causing it is Tech Reborn, I'm not too sure how to fix it as I have little experience with server crashes (I had one before, but I just took out the mod after reading it wasn't server compatible).
Also, if this is your first time making a forge server, this video was the only one that really helped me make one -
Only thing that video doesn't mention that I had to do was adding more ram to the server, also make sure you delete the world that it made when creating the files and make a new one once the mods are in.
One more thing, I don't think you have to take out the client side mods, I kept them in the server and it was fine.
Thank you so much! I was able to get the server to start by getting rid of Tech Reborn. Now I just have to figure out how much RAM this server is going to need because 6 gigs was not enough haha