So I bought a server and I started installing the mods that I knew were functioning fine. I tried them in my singleplayer save and I proceeded to install them on my server. The thing is, that it crashed lol here is the crash report.
Hmm. Can you provide your PC Specs? That could be an issue. Also what mods/modpack are you trying to install? Some of are very twitchy. As well as specs and modpacks, how many people are playing on your server? You need to have quite a beastly PC to have a ton of clients. It's almost like running all those Minecraft clients at once.
I've also had issues with some modpacks. The only thing I know other than re-installing them on the server would be to choose a different modpack and try it.