Stoneblock 2 Server Client Version Mismatched

I've recently finished playing Sky factory 4 with a friend and have decided to move to Stoneblock 2. I had no problem setting up a Sky Factory 4 server, but when I try to logon to my Stoneblock 2 server an error message pops up say that the server requires a higher version than the client I am running, but as far as I know I the most up to date version.