Usually disconnection are due to poor quality or damaged cables, poor cabling or administrator privileges conflicts between ASCOM app.
Be sure the all the software/app that interact with StarGo via Avalon ASCOM driver run with the same administrator privileges.
Is possible to make this check by performing a right click on StarGo, on the interacting software and then clicking on the Compatibility tab. In order to work properly the "Run this program ad an administrator" must have the same status (flagged or unflagged).
Try to replace the USB cable or change USB port.
In case the USB cable is connected to an Hub, is strongly suggested to use Powered Hub.
The StarGo can't be used with step/direction signal output because the motors are directly driven from the CPU.