If your existing modem does not work on a compatible WPS button, you can choose the web-based method. But, if you fail in that process too, due to some errors or difficulties, you have another setup option. Which is the Linksys velop setup without app, which will also guide you to perform the process in the right way. You only need to access the setup window after getting the Linksys WiFi app on your smartphone. https://linksyswifiextender.net/linksys-velop-setup/