I just get message form server room staff:

"Dear all
A big shutdown of our network is coming!
Due to the measurements of the power grid, we have to switch off
the computer network in the whole building from 11 to 13 January 2019.
During this time, no computers will be working and even there will be
no voltage in the electrical sockets.
We are very sorry for the inconvenience, but we have little influence on it.
Best regards
sysadms"

More...