First, I use an ASUS router in AP mode. My router is an EdgeRouter Lite from Ubiquity which has no WiFi.
I am on the 1.1.0 firmware and have been since shortly after it came out.
As I stated earlier, my AP is not powered down. This problem occurs when I enable or disable one of my 6 guest SSIDs – not the one that the OG is connected to. In this case the router has to do some reconfiguration of its bridge and then I run a script to reconfigure the bridges and VLANs so that each enabled guest SSID is on its own VLAN.
Connectivity is lost as soon as I click the Enable button on the web page for the guest SSID. And it remains lost indefinitely after I run the script. Note the AP does not reboot during this change. During this I never see the OG blue led flash quickly indicating a reboot. Yet once I power cycle the OG forcing the reboot, it connects and works just fine with the new AP guest SSID configuration.
I thought it might be related to my VLAN stuff. I separate all guest SSIDs to individual VLANs so that I can use firewalls to isolate each one. When the ASUS enables or disables a guest SSID, it reconfigures bridges and VLANs but puts all the guest SSIDs in the same VLAN as the regular SSIDs. That is why I have to run a script to rebuild the bridges and VLANs to separate them. I have a reserved IP address for the OG within the VLAN subnet it is connected to. I was thinking during the reconfiguration from enable / disable of a guest SSID maybe the OG got a different IP address from the wrong VLAN and then once I ran the script to fix the VLANs, the OG was simply on the wrong IP address. But this would require the OG to have rebooted and I have seen no evidence of that. So I dismissed this idea but explained it for completeness.
When I have lost connectivity to the OG, I can neither get a web page nor ping it successfully. And I have waited at least 10 minutes in some tests.
I do not believe when the OG is in this disconnected state that a ping from the OG will succeed. But I have no way to prove that short of new firmware.