Monitor turns off/on randomly - Any ideas why?

We have three systems that recently received an updated to Windows 10 and now the external monitors blink off/on randomly.  The monitors don't shut down, they seem to simply lose a signal for a few seconds and then come back on.  There is no pattern to the problem, sometimes they will work fine for a bit then they will do it several times in a few minutes, then go an hour before doing ti again.  

The systems are  2 x Latitude 5480 laptops, and 1 - Optiplex 5040 desktop

The laptop screens don't blink at all, it's only the external monitors.  These are the laptops that use the C-Dock instead of a regular port replicator.   

I ran a thorough hardware diagnostics and everything came back fine.

I have updated the chipset, the BIOS, and C-Dock, the video drivers, the cables, and the monitors, and nothing had taken care of the problem.  

The 5040 has also had everything updated that we can think of, but the monitor still blinks.

Any help with this would be appreciated.

Thanks!!