Go through this door to find the old IO server via the Command Cavern. This server can also be reached by exploring the west side of the Command Cavern, walking past one of the drills, and through the door on the ground floor of this area. Simply jump through the vent and land on the platform below to find the server waiting for you. Jump into this vent to find the IO Server. The simplest old server IO can be found by dive into the vent located west of the north entrance to Command Cavern. There are three old IO servers located in the Command Cavern, but you only need to visit one to complete this challenge.