You're running the CMD line as computer 1's admin, attempting to shut down computer 2. Computer 1's admin =/= computer 2's admin, ergo you do not have the rights to shut down computer 2 as computer 1's admin. You have the rights to shut down computer 2 as computer 2's admin, you do not have the rights to shut down computer 2 as computer 1's admin. Being the admin of a single computer does not give you admin rights over every other device on a network. What's wrong with computer 2 that you can't just go shut it down without pressing the power button? Can you not get a display off of it... Is there a virus/malware present that is prohibiting manual shutdown... etc? Why can you not shut it down via it's own machine? Or is this simply for convenience's sake?