The server wants mods this client does not have
Applies to the game client.
What it looks like in your log
Incompatible FML modded server
What causes it
The client was turned away because its mod list does not match the server: missing mods, extra mods, or wrong versions.
How to fix it
Install the exact pack version the server runs. If the server names channels or mods in the kick message, those are the ones to match first.
Not sure this is your problem? Paste your log and Roastd will tell you which of these it actually matched, and what else it found.
Check your own log