Monitor not waking up after switching KVM input I'm using a 2-port KVM switch between my Mac Mini and a Ubuntu desktop computer. I have no problems with the Ubuntu machine waking up when I switch to the inputs. However, when I switch over to the Mac Mini, the monitor stays dark.

This problem only started after upgrading the Mac Mini to OSX 10.11 El Capitan.

FWIW: When I VNC in from another computer, the monitor fires up just fine and I can do stuff just fine. Then I can use the keyboard and mouse hooked up through the KVM switch on the Mac Mini.

Also, I am switching using the physical buttons on the KVM switch; not a hotkey sequence on the keyboard.

Any ideas?
While I do not have an answer to your problem, I can add a "me too" with having issues with KVM's and El Capitan. I have an ATEN CS1944 kvm that works just fine with everything up to and including Yosemite. When I convert machines to El Capitan the the KVM and the machines freak out when the kvm shifts focus away from the El Capitan machine and then ultimately requires a reboot of the affected machine to get things going again.

Tried numerous work arounds and tweaks with no success. Between this kvm issue and the other issues that arose with the converted machines not playing well as XSAN clients (kept randomly failing to auto-mount the xsan volumes) upon machine startup, I had to bite the bullet and fall back to Yosemite on the 2 converted machines that were attached to the KVM.

I guess it will be a wait for KVM firmware updates and or OS X patches / fixes to try again after the product matures a little more. Keeping the fingers crossed and continuing research for a fix.

Good luck with resolution to your issue as well.