R6900P

When I use Nighthawk to turn off and on various device access to my R6900P Router the device that has regained access shows the WiFi is connected but no access to the modem and the internet.  This only happens to devices that are removed through Nighthawk from the router and turned back on.  I have tried to restart the device (computer, tablet or phone) as well as renewing the DHCP license and clearning the DNS cache.  Still does not work.  Thanks for any help.