Recently i logged on to iDRAC for one of our Dell R720 servers,however somehow the console redirection did not work at all. I kept on seeing No Signal on the Virtual console Preview. I tried Rebooting the server but that did not help. Finally i clicked on Reset iDRAC and this did the trick. It may take around 2 -5 minutes before you can access iDRAC page again. I had to power on the server through iDRAC before anything showed up on console. Hope this Helps.