R6700v3

Is the wifi enabled on the router? Try the wifi button press for wifi to turn it ON if it's been turned off. 

Review the user manual for this router for that button feature.

Has a power off for 1 minute then back ON with the ISP modem and router been performed since last update?
Be sure to restart your network in this sequence:
Turn off and unplug modem.
Turn off router and computers.
Plug in and turn on modem. Wait 2 minutes for it to connect.
Turn on the router and wait 2 minutes for it to connect.
Turn on computers and rest of network.

Has a factory reset and setup from scratch been performed since last FW update? A complete pull of the power adapters for a period of time after the factory reset then walk thru the setup wizard and setup from scratch. Recommend setting the default DHCP IP address pool range to the following after applying and a factory reset: 192.168.#.100 to 192.168.#.200