In my case it helps to restart the service lightdm (sudo service lightdm restart) - this works around 50% of the time, but in some cases the system freezes afterwards and a hard reset has to be performed.
Another issue is that if the second monitor goes to sleep it is not waking up afterwards. -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1574005 Title: HDMI connection not working on Ubuntu 16.04 and GeForce GTX 960M To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1574005/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp