This is an elevated privilege issue with your Internet Download Manager in Windows 10. It prevents the program from downloading files from websites or videos from YouTube you were once able to download in old Windows versions. Normally, the software tries to download a file and later reports error of 'not able to connect to the server or it has been disconnected by remote server' dialog.
Having tried every process to troubleshoot the problem without coming up with clear solution you wonder what the cause of the problem may be. You have scanned your system over and over again for Malware and Anti-virus without report of any malicious software. The program seems to start well but fails to download and displays error of false server in every attempt, mostly especially, with YouTube videos.
There is a quick solution to this problem if you are running Internet Download Manager in Windows 10. The step-by-step information below would be of valuable use to you in finding solution in time.
STEP 1: Right-click on your Internet Download Manager on your desktop and select 'Properties' to continue.
STEP 2: Click 'Compatibility' tab at the top of the 'Internet Download Manager Properties' dialog.
STEP 3: Tick the little box by the side of 'Run this program as an administrator' , click 'Apply' and click on 'OK' to close the dialog.