Thank you for your post. To connect to an external GPS on Windows 10, there is a two-step process. The first step is to ensure that your device itself registers that an external GPS is connected to it. The second step is to open Avenza Maps, go to Settings > GPS and refresh the list until the GPS unit is displayed. Once it is displayed, please select it as the GPS to use. Please note that we have only tested a handful of GPS brands/models, and as such cannot guarantee that all GPS devices will work with Avenza Maps. If you continue to have any problems or have any other questions please let us know.