I THINK that the Verizon box is actually its own modem/router combo. So in essence you have to do one of two things; 1. shut off the "router" portion of the Verizon box so it operates solely as a modem and then use the Deco units, or 2. turn the deco units into Access Points (APs) which is done through the Deco app settings. If my hunch is correct, both are operating as the wireless router and could be throwing conflicting signals (networks) out that is causing the internet issue.