[How Do I?] How to update my RO2/RS dedicated server?

Hi, I set up my server for me and a few friends to play on when the game went free for 24 hours a few weeks back and it all went well.

I wanna play some now but it seems the server isnt updated (mismatch dlc error ingame etc) but I can't find how to update it. I tried

"SteamCmd +login Username Password +force_install_dir c:/ro2server +app_update 234510 validate" (obviously with my username and password) but it says

ERROR! Failed to install app '234510' <invalid install path>

This is the same bat file i used to make the whole server so I don't get it. Please help.