It's from a singleplayer point of view, yes. But it should apply to your server too. Try the same modpack in singleplayer game and you should get the same errors. Follow the guide from there and apply the changes you make also to the server files.
There is really no easy "press this button" to solve these issues. Managing a Minecraft server is not exactly easy, especially when running a custom modpack.
Note: This could also be caused by a modpack mismatch between the client you use to connect and the server itself. You are sure you're using the correct client?
Edit: Actually, I think a mismatch between client and server is the reason for this error. You need to use the same mods and configs in your client as you run on the server. Though, i'm not exactly an expert on these issues. You might have to wait for someone with more knowledge to notice this thread, i'm more a network guy.