@brad put the Oxygenator in the Shelter, not on a platform.The RTG, Radioisotope Themoelectric Generator, is a power generator. You get one for free in your starting Shelter.The moment a tether line breaks place another tether. A tether connects to another tether at a slightly longer length than your player does. Also the T key is set to place a tether by default, no need to shoulder mount them. I would recommend shoulder mounting something like a work light or small solar panel instead.Your base will prioritize powering the player, and/or batteries in the player's inventory, before powering the base. The power lines went red because your base could only power the player, and it then went back to powering the base.If you hover your mouse cursor over your player character a compass will appear.I also highly recommend reading the in game Astropedia in it's entirety!