Navigate to your RimWorld installation folder. Steam Path: ...\Steam\steamapps\common\RimWorld\Mods .
Launch RimWorld, go to the Mods menu, and ensure Harmony (if required) and the Multiplayer mod are checked. Critical Warnings rimworld-mp-steam-fix-for-v1-3-3117-zip
RimWorld v1.3.3117 (a specific build of the Ideology expansion era). Navigate to your RimWorld installation folder