Add the deco again. 1. Make sure your old router can access internet when hook up to your modem. 2. Connect the main deco to the old router at LAN port, connect your phone to the old wifi to set up the deco. 3. Once set up finished, connect the deco back to your modem. Check the IPv4 IP address under Settings>Advanced. 4. You can also use another phone to set up the deco