I have an ASUS monitor attached to HDMI using plugable device with a mac book air. The display only turns on after reboot. If laptop goes to sleep the monitor will not turn on after wake up.
Thanks for posting! I will be happy to help. You don’t mention what Plugable product you are using, but assuming you are using one of our USB graphics adapters, we do not recommend our USB graphics products for use with Mac OS X as many users experience issues running DisplayLink-attached USB displays with OSX 10.9.x (Mavericks) as well as 10.10 (Yosemite) and 10.11 (El Captian). Because the behavior can be undesirable on many Macs. Plugable and DisplayLink have opened tickets with Apple to resolve the issues, but we have no indication if or when they will chose to do so. (As I understand it, DisplayLink has fixed what they can at the driver level, but there’s issues related to the OS itself.
That being said, the only advice that I am able to give is that you ensure that you are using the most recent DisplayLink driver for Mac that can be downloaded here -> http://www.displaylink.com/downloads/osx. I do apologize for this detail if you are in fact using one of our USB graphics adapters, and we will gladly assist in a return for refund if you wish as we would not want you to be stuck with a device that does not meet your needs. Please reach out to us directly at firstname.lastname@example.org and reference Ticket 140549 in the subject line and we can get the refund process started.