If your ST3300G3UA is connected to a computer running macOS, and the network connection stops working after you wake the computer up from sleep mode, you can temporarily resolve this issue by unplugging and plugging the ST3300G3UA back into your computer. This will resolve the problem until your computer is put to sleep again.
To permanently resolve this issue, make sure you have downloaded and installed the latest macOS drivers from the ST3300G3UA product page. If these latest drivers do not resolve your issue, check to see if your ST3300G3UA is revision B. This is marked on the ST3300G3UA's ID label and box. If your ST3300G3UA is not revision B, contact StarTech.com support for further assistance.