WiFi Capable Mobile Devices Act of 2017 This bill directs the Federal Communications Commission (FCC) to issue rules to ensure that providers of mobile broadband Internet access service supported through the Lifeline Assistance Program offer mobile devices that are capable of: (1) receiving WiFi or other wireless broadband signals using unlicensed spectrum, and (2) sharing a mobile service connection (commonly referred to as "tethering") with other compatible hardware or devices. (The Lifeline program provides discounts on telephone service to qualifying low-income consumers.) The FCC must also provide incentives to such providers to work with schools and libraries to conduct outreach to those eligible for Lifeline assistance.