This client and some server disagree about the mod list
Applies to the game client.
What it looks like in your log
Client has mods that are missing on server:
What causes it
The client compared mod lists with a server and they differ. Forge logs this both when it pings a server sitting in the list, where it only marks that one entry incompatible, and when a join is actually refused, so the timestamp is what tells the two apart.
How to fix it
Check this line against the time of the connection attempt before blaming it for anything. If it does belong to the server being joined, match that pack exactly, mod for mod and version for version; if it belongs to an idle entry in the server list, it is background noise.
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