BRB50 loses WIFI internet after firmware update

My RBR50 that has been humming along for 2.5+ years has suddenly sporadically losing the ability to provide internet connectivity. The problem started after I applied the most recent firmware update. Amazon Alexa devices, fire tablets and other smart devices are not affected but laptops iphones and android smartphones are. The netgear app shows a fast internet connection but phones etc that worked all day suddenly start reporting that "the internet may not be be available". A Xfinity router (which has been on and transmitting for months) provide internet connectivity without an issue.