Usually with an ethernet cable. (sorry, you kind of lobbed that one out there for me)
Are you having issues with it?
If it truly is a modem/router combo device from verizon, you'll want to either place it in modem only/passthrough mode or you'll want to place the RAX in AP mode. Or you'll have a double nat and have many different issues. If you go the route of putting the verizon device in passthrough/modem only mode, I'd contact them to see the best way to do so. They're going to be the experts on their devices.
If you go the router of placing the RAX in AP mode, I'd disable the wireless on the verizon device to reduce interference.