BR500 upgrade to 5.1.0.15

EDIT: I just looked at the firmware update instructions and it says to perform the update via the app or the Insight portal, so you were definitely following instructions. But that ... does NOT sound like a good idea. For one, if anything goes wrong and the router loses connection with the cloud portal you risk bricking or seriously messing it up. Not your fault, I'm just wondering how Netgear thought this was a good idea.

I don't have a BR500, but I can tell you from experience: never, never, NEVER upgrade a network device's firmware from an app or wireless client. Do it only from a wired device, preferably from one that's on the same LAN. Every time I've attempted updating over an app or Wi-Fi (even when there's no official warning not to) either settings get messed up or the device bricks.