Voyager focuser control can manage all focuser with ASCOM driver, be sure you focuser have ASCOM driver and check, if you connect this to more than a one application , that this driver support more than one client connection.
Leave Voyager open for for first the driver if you want to use poth. If you want to open POTH before be sure to use it in admin mode if your driver open another instance.
Strange that a focuser with ASCOM cannot be used with Voyager, is the first time.
Which version of ASCOM interface use this driver ?
Probably is not compliant or doesn’t match the ASCOM Paltform version you have installed ?