VVDI MB Tool displays error when prepared key files:
Internet configuration not correct. please check internet or change isp and retry!

Tried old and new version. Reinstalled new version and firmware , with no change

Solved!

Well the issue is windows. I installed it on an ancient windows 7 PC and it works fine. Windows 10 did just push an update and seems to have broken the MB. I have checked and all windows security stuff is off + has exemptions for the tool. Worked prior to the last update

(Thanks to Jerry King)