Thanks for the reply. I have visited these options and will be ready for them should this happen again.
The wireless networks are not available, their SSIDs are not broadcast. My wireless clients that were connected to a WiFi network have their connection killed, and their status says they are not connected to any Wifi network.
I usually login to the router on a wired Ethernet connection. I do not think the router passes traffic to other wired Ethernet ports on the router, but I am not sure. Of course, further downstream, my IP address from DHCP is not disturbed, and if there is an Ethernet switch with multiple clients on, they can still talk to each other. But in this case, there always is an Ethernet switch between the clients and the router.
InControl shows the host to be down, in fact I have it send email notifications, and I receive them.
No UPS or surge protectors, and my power is generally stable, no blackouts, no problems with any other electrical equipment at that time of these occurrences.
These incidents have happened once every two or three months, totaling 4 times.