If the displays connected to your MST hub do not wake up after your computer goes to sleep, change the input on the monitor(s) from Auto to the correct input (for example, DisplayPort or HDMI). This prompts the monitor to send its identification data to the correct port instead of scanning for ports when the signal is lost.
After you select the correct input on the monitor(s), press the Scan button to initiate the handshake (EDID) process. For more information on the Scan button, refer to the following FAQ: http://www.startech.com/faq/mst-hubs-scan-button.
If you set the monitor to the correct video port and press the Scan button and the issue is still not resolved, you need to disable sleep mode on your computer. To disable sleep on a computer running a version of Windows, complete the following:
Open Control Panel.
Click Power Options.
Note: Depending on how you have the View by options set in Control Panel, you might have to click Hardware and Sound to see Power Options.
Click Change plan settings for the plan in use.
For both entries, change Put the computer to sleep to Never.
Click Save Changes.