NETGEAR Nighthawk RAX120 router Wi-Fi keeps disconnecting

The checks in more detail

If every device and the wired connection fail together and a reboot cures it, the router is the problem and the restart and overheating pages apply, because the RAX120 runs hot and the community found that a failed thermal sensor lets it heat without the fan spinning up. If only a few devices drop, give each Wi-Fi band its own name in Wireless settings so that you can pin devices that struggle to the 5 GHz or 2.4 GHz band, and set the 2.4 GHz channel to 1, 6 or 11 so that it does not overlap with neighbors.

On the 5 GHz band, set the channel width to 80 MHz and choose a channel without DFS if radar events make the router hop channels and drop devices; the router logs a DFS event when it does, and a non-DFS channel stops it. Other causes are device-side. A phone that holds on to a weak signal instead of moving to a stronger one drops at the edge of the range, so add a mesh satellite or move the router. Power saving on a laptop's Wi-Fi adapter disconnects it when idle, so set the adapter to maximum performance.

Turn off Smart Connect for a test, since band steering can bounce a device between bands. Check the router's firmware and update after reading recent posts. Put the router in the open and out of a cabinet. Look at the router's event log for repeated disconnect messages with times. A drop of the internet only, with the Wi-Fi staying up, may be the cable line and the modem, so check the modem's signal levels. If drops continue with a cool router, clean channels and updated firmware, contact NETGEAR, mentioning the community findings.