Popular tethering app called FoxFi appears to no longer be working on Verizon unlimited data plans. Many users have noticed that the ‘no root required’ tethering app, hasn’t been working lately devices registered with a Verizon unlimited data plan. This was posted online and the issue quickly escalated many other users experiencing the same problem.
Many users of FoxFi are seeing a subscription request from Verizon when trying to use the app, which is typically the screen that you see when you try and tether a device with a Verizon plan without having signed up for a tethering plan from Verizon. Due to this, people are speculating that this something Verizon is doing intentionally.
It is always possible that FoxFi will issue an update to the app that will bypass Verizon’s subscription check. Unless this happens, you may be stuck with not being able to use FoxFi.Source: Droid Life