I have the same problem on 16.04.2 Xenial since upgrading the Kernel to 4.4.0-75 yesterday. Booting the the older kernel version 4.4.0-72-generic seems to be a workaround.
-- 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/1686189 Title: External monitor connecting problem To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1686189/+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