Most of the time, NetGear router keeps disconnecting issues occur because of firmware issues. Download the latest firmware from the company's website and upgrade it. If this does not help, then try updating the third party firmware like DD-WRT or Tomato. If this does not help, it could be an issue with your ISP. You can try factory resetting your router and reconfiguring it from scratch. If this does not work, contact your ISP and get a replacement.