To simplest and quickest way to get back online:

  1. Turn off the router installed, typically in a utility cupboard. 
  2. Turn off the wireless router.
  3. After 5 minutes, turn both devices back on, they'll take between 6 and 10 minutes to boot back up. 
  4. Reboot any devices connecting to your wireless router.
  5. Contact customer support if issues persist.